- Open Access
Fruit ripening: dynamics and integrated analysis of carotenoids and anthocyanins
BMC Plant Biology volume 22, Article number: 27 (2022)
Fruits are vital food resources as they are loaded with bioactive compounds varying with different stages of ripening. As the fruit ripens, a dynamic color change is observed from green to yellow to red due to the biosynthesis of pigments like chlorophyll, carotenoids, and anthocyanins. Apart from making the fruit attractive and being a visual indicator of the ripening status, pigments add value to a ripened fruit by making them a source of nutraceuticals and industrial products. As the fruit matures, it undergoes biochemical changes which alter the pigment composition of fruits.
The synthesis, degradation and retention pathways of fruit pigments are mediated by hormonal, genetic, and environmental factors. Manipulation of the underlying regulatory mechanisms during fruit ripening suggests ways to enhance the desired pigments in fruits by biotechnological interventions. Here we report, in-depth insight into the dynamics of a pigment change in ripening and the regulatory mechanisms in action.
This review emphasizes the role of pigments as an asset to a ripened fruit as they augment the nutritive value, antioxidant levels and the net carbon gain of fruits; pigments are a source for fruit biofortification have tremendous industrial value along with being a tool to predict the harvest. This report will be of great utility to the harvesters, traders, consumers, and natural product divisions to extract the leading nutraceutical and industrial potential of preferred pigments biosynthesized at different fruit ripening stages.
Fruits are important and health-promoting food resources and are a part of our diet as a potential source of nutrients . With the development of research and analytical biotechnological approaches, the bioactive compounds in fruits have been identified and considered for their efficacy as nutraceuticals and industrial products. Nutrients like vitamins and minerals cover 85% of the nutraceutical market, followed by antioxidants and herbal extracts. The bioactive compounds present in fruits are utilized as nutraceuticals, cosmetics (sun screen, antiaging formulation,) and in oenology . The multifold uses of fruits have been attributed to the presence of several bioactive compounds, such as chlorophyll, carotenoids, anthocyanins, betalain, phenols, tannins, flavonoids, glycosides, and many more, which are known for their nutraceutical properties and are capable of replacing pharmaceuticals . Among these, fruit pigments like chlorophyll, carotenoids, anthocyanin and betalain have been recognized world-wide as safer natural colorants for several industries such as food and confectionary, textiles, cosmetics, and pharmaceuticals [4, 5].
Fruit color is an indicator of its stage of maturity, freshness and quality and serves as an important parameter in their classification . As the fruit passes through various stages of growth and maturity, the variations in fruit color are observed due to biosynthesis and degradation of pigments in developing fruits. The accumulation of pigments is largely governed by the various maturation stages, during fruit ripening, which in turn is dependent on biotic and abiotic factors along with species’ genetic makeup. During maturation, fruits undergo several biochemical and physiological changes that alter its bioactive composition . The changes in pigments are markers of the development stage and the physiological condition of the fruit which are essential for optimal storage and postharvest management . However, there is lack of data and limited research studying the changes in bioactive compounds during ripening. Also, to date, most of the research on ripening in fruits has been focused on the growth regulatory hormones, but the role of pigments as an asset to ripening has been unexplored. Apart from making the fruits colorful and enhancing its consumer appeal, pigments add value to the ripened fruits by enhancing the net carbon pool, antioxidant status, nutraceutical properties and industrial use. Moreover, pigments could serve as an agro-industrial tool to assess the ripening status and quantifying ripening. Consequently, a strong need was felt to study pigment accumulation in fruits as a platform for future research prospects on biofortification of fruits. Furthermore, the extraction and characterization of pigments in ripened fruits could lead to discovery of novel, unexplored pigments with probable bioactivity and subsequent applications. Keeping this in consideration, here we report pigment dynamics in ripening viz-a-viz regulatory mechanisms involved in pigment biosynthesis, metabolism, stability, and storage along with prospects to enhance desired pigments of nutraceutical and industrial value in fruits.
Pigments in fruits
Fruit color signifies a genetic trait with ecological and nutritional worth. Plants mainly make use of color for seed dispersion and to attract animals. The other adaptive challenges were entrusted on fruit color by environmental factors and domestication further resulting in diversification. The unprompted mutations occurring repeatedly in pigment biosynthetic pathways lead to variations in fruit color which were often propagated. In the recent decades, the pigmentation pattern was further enriched by introgression breeding coupled with the unravelling of genetic determinants underneath fruit pigments .
The emergence of these pigments as a result of fruit ripening has multifold prospects for the growing plant. The chlorophyll content and development of chloroplasts at mature green stage affects the net carbon yield of a ripened fruit .
Chlorophyll and carotenoids are the main photosynthetic pigments in plants and play a vital role in enhancing the net carbon yield of the plant . These pigments are embedded in photosystems II and I and are involved in capturing and utilization of light energy by the plant, via the photosynthetic electron transfer and thereby influence the final yield of fruits . It has been reported that green tomato fruit may contribute as much as 10 to 15% of the total fixed carbon of the fruit [12, 13]. Furthermore, the down-regulation of the Calvin-Benson cycle enzyme fructose-1,6-bisphosphatase in green tomato fruit resulted in a 15–20% negative impact on fruit development and yield  further demonstrating the importance of chlorophyll to green fruit..
Chlorophyll a and b are present throughout the photosynthetic machinery whereas carotenoids like β-carotene, violaxanthin, antheraxanthin, zeaxanthin and lutein are mainly present in antenna systems of light harvesting complexes [15, 16]. During periods of high-light stress, plants adopt to the phenomenon of photoinhibition leading to reduced levels of light capture. However, carotenoids inhibit photoinhibition by scavenging the free radicals and undergoing conformational changes (VAZ cycle and Lx Cycle) to protect the plant from the adverse effect of high light  and prevent photoinhibition and thereby increase the final carbon pool in the fruits . Also, anthocyanins act as UV filters, and protect the plant from high light at low temperatures, thus reduce photoinhibition and open a window for photosynthesis.
Apart from their crucial role in photosynthesis, pigments like carotenoids and anthocyanins enhance the antioxidant status and therapeutic potential (Table 1) of the fruits along with other compounds like polyphenols, tocopherols, vitamins and catechins .
Carotenoids like β-carotene, lycopene, zeaxanthin, and lutein are the major antioxidants in fruits and act as scavengers of free radicals. Lycopene, lutein and astaxanthin and the colorless carotenoid precursors phytoene, phytofluene have also been associated with a decreased risk of cancers including prostate cancer [39,40,41], colon , and lung . These benefits, of a carotenoid rich diet, could have a significant contribution to human health and previous authors have suggested that manipulating their metabolism could contribute to this goal .
Among the carotenoids and their cleavage products, the highest oxidation potential of 0.94 V has been reported for bixin, an apocarotenoid, obtained from the seed arils of Bixa orellana  and thereby possess tremendous industrial potential (Fig. 1). Bixin has also been described as having anti-cancer properties towards osteosarcoma, breast, colon, prostate, anaplastic thyroid, and papillary thyroid cancers  as well as various potent pharmacological activities, including anti-inflammatory and antioxidant properties and is a promising candidate for the treatment of multiple sclerosis due to its ability to prevent neuroinflammation in mice primarily by scavenging ROS .
Berries have also been found to be richest source of anthocyanins among fruits, and blue berries have been reported to be the richest source of antioxidants with a TEAC (Trolox equivalent antioxidant capacity) value of 14.98 mM Trolox/100 g of dry weight due to high levels of proanthocyanidins and anthocyanidin .
Apart from their health benefits, pigments extracted from fruits have been found to have numerous applications as food colorants, in cosmetics, textiles & pharmaceutical industry  (Fig. 1). Considering the multifold applications of pigments, several extraction techniques ranging from conventional Soxhlet to the usage of novel techniques like electric field extraction have been designed to extract the desired pigments in optimum quantity and quality from fruits at various developmental stages of ripening (see Table 2).
Among the several pigments present in fruits the major pigments such as chlorophyll, carotenoids, and anthocyanins possess diverse pigment functionality as they are essential for photosynthesis, possess multiple bioactivities, potent antioxidants, therapeutic properties, and industrial use, therefore an in-depth analysis of the factors regulating their biosynthesis, metabolism and storage during ripening is inevitable. This will further aid in designing biotechnological tools to enhance the production of these highly beneficial pigments in fruits.
Regulation of pigment dynamics in fruit ripening
Pigment change during fruit ripening is a tightly controlled phenomenon signaled by plant growth hormone, several transcription factors, gene families, enzymes of the pigment biosynthetic pathways, and environmental stimuli . Also, signaling molecules such as nitric oxide, melatonin, hydrogen sulphide  and sucrose have been highlighted for their role in accumulation of pigments during various fruit ripening stages (for details, see review by ). The ripening of fruit results in color change owing to pigment biosynthesis, degradation, and sequestration with the aid of development of new organs such as fibrils in pepper and plastoglobules in other fruits [71, 72]. Also, the pigments undergo several biochemical changes post synthesis to enhance their stability leading to the production of novel cleaved pigment products with probable bioactivity. In addition, mutant studies in the last two decades have uncovered the role of the regulatory mechanisms and have provided a platform to enhance the production of desired pigments with biotechnological tools .
Manipulation of fruit de-greening enhances carbon yield
As the fruit begins to ripen, the degradation of the green pigment chlorophyll, is initiated to promote remobilization of nutrient and promote biosynthesis of vitamins. The de-greening of fruits is important to promote detoxification of chlorophyll released from its binding proteins . Light, along with the growth hormones ethylene, ABA and jasmonic acid, signal specific transcription factors (TFs) (see Fig. 2), which activate the functioning of the CCG (chlorophyll catabolic genes) involved in chlorophyll degradation [75, 76]. However, any mutation in the enzymes or signaling by the regulatory TFs could lead to a stay-green phenotype, which has recently been reviewed by Zhu et al. . However, slowing down of chlorophyll degradation is an effective strategy to enhance the fruit quality as it extends the time period of photosynthesis in the developing fruit, enhances the assimilation of carbon, soluble solid content and nutraceutical composition of fruits . Several reviews have evaluated the role of fruit photosynthesis in carbon gain [10, 78,79,80,81] and the link between photosynthesis and the formation of key vitamins . Besides, an insight into the regulation of chlorophyll degradation pathway has enabled food technologists to enhance the storage and shelf life of food by delaying de-greening with effective use of several chemical compounds like 1-MCP (1-methyl cyclopropene)  elevated carbon dioxide, , melatonin , and chlorine dioxide  resulting in inhibition of signaling by growth hormones, and suppression of genes which promote chlorophyll degradation (see Fig. 2). However, there are many fruits which remain green even when ripe, like some varieties of apples (Granny Smiths, Crispin), pear, green grapes, limes, guava, and cucumber, to name a few. “Stay green even when ripe” phenomenon has been attributed to suppression of genes which encode the chlorophyll degradation enzymes  and insensitivity to ethylene as shown in Nr (never ripe) mutants in tomato. The variations of color in tomato clarifies that regulation of carotenoid biogenesis is unique for each species. Recently, Solanum habrochaites (SH; green -fruited) was studied to decipher the molecular reasoning for green color retention. i) In SH a shift towards the β-carotene branch of carotenoid biosynthesis was found missing and both α- and β (carotene) branches were found to make equal contributions, ii) SH fruits were found to be insensitive to ethylene induced carotenogenesis, as in spite of emitting high levels of ethylene, they remained green, iii) SH fruits were found to retain the proteins related to photosynthesis and were lacking in proteins involved in conversion of chloroplasts to chromoplasts, iv) lack of carotenoid accumulation in spite of uncompromised expression of chromoplast specific genes such as PSY 1(phytoene synthase1) and LCYB (lycopene β-cyclase) in SH due to probable blocking by SNP’ (single nucleotide polymorphisms) resulting in lack of abundance of key proteins PSY1 and LCYB, v) diminished levels of homologues of fibrillin (FIB) like PAP3 (plastid lipid-associated protein) and CHRC (chromoplast-specific carotenoid-associated protein) involved in sequestration  However, carotenoid biosynthesis is independent of chlorophyll retention and is carried out in both red (normal pace) and green (slow and delayed) phenotypes with the green lines showing the presence of both the thylakoid and the plastoglobuli in the same plastid .
Chloroplast to Chromoplast: accumulation of starch and carotenoids
The degradation of chlorophyll in fruits like tomato and pepper is accompanied by a well-regulated conversion of chloroplast into chromoplast (see Fig. 3), accumulating carotenoids and result in a visible color difference from green to yellow to orange to red . Carotenoids are sequestered in plastids (chloroplast and chromoplast) at high levels. In the chloroplast xanthophylls are produced for their photosynthetic utility in the thylakoid membrane . However, during ripening, breakdown of the thylakoid takes place coupled with accumulation of carotenoids like lycopene in the membrane along with synthesis of membranes as sites for carotenoid biosynthesis, coupled with increased number and size of plastoglobules [72, 92]. In the chromoplasts, the plastoglobules are highly enriched with esters of carotenoids and enzymes involved in carotenoid metabolism (for details see review ). The FIBs play a crucial role in development of plastoglobules and fibrils in fruits for storage of carotenoids. In a trial by Simkin et al.  the role of FIB gene was assessed and it was found that it delayed thylakoid loss in differentiating chromoplast and resulted in an increase in plastoglobuli number and thereby increased the concentrations of carotenoids like β-carotene and lycopene .
The chlorophyll content of an unripe fruit such as tomato has been found to be directly linked to the sugar content of the ripened fruit, thereby affecting the nutritional quality and taste of a ripened fruit. Therefore, the regulatory mechanism involved in chloroplast development and accumulation of chlorophyll are crucial. DET1 (De-etiolated 1) and DDB1 (UV-damaged DNA-binding protein1) control chloroplast number, size and development as negative regulators , Also GOLDEN2 LIKE TFs GLK1 and GLK2 play a crucial role in chloroplast development and accumulation of chlorophyll  along with its homolog APRR2-LIKE (Arabidopsis pseudo response regulator2)  (see Fig. 3). The transcriptional activation of GLK 2 and APRR2-LIKE genes is carried out by TKN2 and TKN4, the two KNOX (Class I KNOTTED1-LIKE HOMEOBOX) proteins . In addition, ARFs (auxin response factors) are involved in transcriptional regulation of fruit ripening by repressing or activating transcription of auxin responsive genes. In tomato, ARF4 has been reported to negatively regulate chlorophyll accumulation in the fruit along with starch biosynthesis. A reduced ARF4 content resulted in a dark green fruit with enhanced chlorophyll, increased chloroplast number accumulated more starch at early stages (green fruit) resulting in more sugar and higher soluble solids at ripening stages (excess starch broken down into sugars) . While ARF6A content was found to be directly proportional to increased chloroplast, chlorophyll, rate of photosynthesis and sugar accumulation as it bound to promoter of GLK1 and positively regulated its activity . Similar findings have been reported for ARF10 being an activator of GLK1 and thereby promoting chlorophyll accumulation . An overexpression of GLK2 has been found to increase the total carotenoid content, sugar and fruit starch . Also, in tomato, with the development of chromoplast the genes for lycopene synthesis are upregulated , while the enzymes involved in lycopene metabolism such as lycopene-e-cyclase (LCYE) and LCYB are downregulated . Therefore, at the ripe stage, chromoplasts are completely developed and become a reservoir of carotenoids and thereby appear red.
With the development of chromoplast the carotenoids which would determine the final fruit color are accumulated and the predominant carotenoid shape up the final form of its deposition which is crucial for color, bioavailability, and stability of the carotenoid. This phenomenon has been demonstrated for fruits of Physalis pubescens L. (yellow), Physalis peruviana L. (orange), and Physalis alkekengi L. (red) wherein the yellow and orange fruit of Physalis showed gradual accumulation of β-carotene and lutein at varied concentration, justifying their different hues on ripening. However in the red fruit of Physalis (on being fully ripe) traces of β-carotene, and high levels of β-cryptoxanthin and zeaxanthin were reported . Therefore, the development of chromoplast not only initiate value-addition of color tones but enhance the nutritional efficacy of the ripened fruit. Also, for the fruits which “stay green when ripe” there are prospects for conversion of chloroplast to chromoplast and enhancement of nutritional value synthetically by the overproduction of phytoene with the crtB enzyme (bacterial PSY enzyme) as demonstrated recently in leaf chloroplasts resulting in reprogramming of plastid-nucleus interactions leading to development of chromoplast and subsequent carotenoid biosynthesis . The regulation of chromoplast biogenesis is beneficial for both biosynthesis and storage of carotenoids (For details see review ). Therefore, research on chromoplast differentiations channelizes development of fruits with augmented carbon yield and sugar when ripe along with enhanced production of carotenoids with multifold health benefits.
It has been shown on several occasions that secondary metabolism and, particularly, plastid metabolism is not only transcriptionally but also post-transcriptionally regulated. Recent developments in technologies based on mass-spectrometry has paved the way for a deeper coverage of protein expression. This has shifted the focus on translational and post translational protein expression in tomato and other fruits, which is currently limited to transcription, thereby adding a novel dimension to the already existing data on transcriptomic, metabolomic and genomic resources . The role of Clp protease in chromoplast development and carotenoid accumulation in tomato fruit ripening has been investigated recently. These researchers concluded that Clp protease work in coordination with specific chaperones that lessen the protein folding stress, enhance the stability of enzymes involved in carotenoid accumulation and inhibit carotenoid degradation . In a yet another trial, CHLORAD (chloroplast-associated protein degradation proteolytic pathway in transition of chloroplast to chromoplast has been reported. These researchers emphasize on the crucial role of chromoplasts in fruit ripening and suggest strategies for bioengineering based crop improvements .
Carotenoid biosynthesis pathway: a reservoir of nutraceuticals
The expression of carotenoid pigment is regulated at three important stages: biosynthesis, degradation, and lipoprotein sequestering structures, respectively. The regulation of carotenoid biosynthetic pathway in fruit ripening (see Fig. 4) is multifold and carried out via signaling by plant growth hormones, enzymes of the pathway and environmental stimuli such as light. The network of TFs and growth hormones such as ethylene and ABA play a critical role in activation of ripening genes. Together they regulate accumulation of carotenoids (in chromoplast) and anthocyanins (in vacuoles). Among the MADS BOX family genes positively regulating ethylene signaling and carotenoid biosynthesis ripening inhibitor (RIN) is reported as the master regulator. Studies on mutants ripening-inhibitor (rin), non-ripening (nor), and Colorless-nonripening (Cnr) have led to novel findings in the ripening process of climacteric fruits like tomato . It has been proposed to generalize physiological attributes in these three mutants; i) in all development occurs up to the mature green stage, with full size fruit yet do not proceed to ripening, ii) all fail to emit ethylene associated with ripening and are unresponsive to exogenous ethylene, however iii) they retort to ethylene in other fruits and tissues induced with ethylene responsive genes. To sum up, these features indicate that all three mutations influence the phenomenon of ripening, essential for ethylene induction along with activities which cannot be compensated by ethylene alone and therefore all three genes are probably conserved regulators influencing even non-climacteric fruit ripening. Recently, fruits deficient in RIN (generated by CRISPR/Cas9) led to partial ripening with only 10% concentration of ethylene and carotenoids in comparison to the wild type . Other transcription factors initiated by ethylene signaling to positively regulate carotenoid biosynthesis are TAG1 (tomato agamous 1), TAGL1 (tag-like1), FRUITFULL1/2, ETR1(ethylene receptor 1) ETR6 (ethylene receptor 6) and HB1 (HD Zip homeobox protein) (see Fig. 4). On the contrary, PYR/PYL9 (pyrabactin resistance/ pyrabactin resistance - like), AP2a (apetala2), ERF6 (ethylene response factor 6) are negative regulators of ethylene signaling. Along with ethylene, the regulatory role of ABA in carotenoid biosynthesis by exercising control over plastid development has been emphasized . As per recent findings of Kai et al. (2019), ABA signaling is mediated by its promoter PYR/PYL9, which regulates the quantity and quality of carotenoid in fruit ripening . These researchers highlighted that in comparison to wild type, over expression of PYL9 lead to on early ripening onset (due to excessive ABA accumulation at mature green stage simultaneously inducing release of ethylene), followed by maximum ABA accumulation at breaker stage resulting in a drop in ethylene levels due to negative crosstalk between ABA and ethylene, thereby affecting fruit color . Furthermore, the crucial carotenoid biosynthetic genes, encoding ethylene regulated PSY1, and the other enzymes like carotene isomerase (CRTISO) and LCYE were reported to be regulated negatively by PYL9 . In contrast, LCYB was positively regulated by PYL9, thereby limiting the entry of metabolites in the lycopene pathway and channeling the carbon towards β-carotene and ABA (similar findings were reported by ). These researchers confirmed that ABA signaling, mediated by PYL9, regulates the genes related to release of ethylene, metabolism of pigment and degradation of the cell wall . Also, curbing the expression of NCED1, which is a vital gene for biosynthesis of ABA, upregulated the production of ethylene and PSY1 and negatively regulated the production of LCYB resulting in enhanced levels of β-carotene and lycopene . Along with the regulatory action of growth hormones the enzymatic regulation plays a critical role in carotenoid accumulation. The over expression of enzymes like DXS (deoxy xylulose5-phosphate synthase) and DXR (deoxy xylulose5-phosphate reductoisomerase) involved in regulating the carotenoid flux have been reported to increase the concentration of carotenoids  and similar findings have been reported for the other key regulatory enzymes PSY and CRTISO . The PSY genes are sensitive to periods of stress, scarcity of water, excessive light, ABA, salinity, and fluctuations in development of the plant. There are three isoforms of PSY genes reported in grasses (Poaceae)  and fruits like tomato possess PSY1 in fruits, PSY2 in leaf tissues and PSY3 in roots under stress [117, 119]. In maize roots, PSY3 expression was induced in periods of stress like drought leading to an increase in the production of ABA and escalation of the carotenoids . In addition, as per recent findings it has been suggested that the PSY gene family compensates for the loss of PSY1 as reported in a yellow pepper variety, Micro Pep Yellow .
The PSY genes are positively regulated by transcription factor RIN and negatively regulated by SGR1, PIF1 and RAP2.2 . A light-induced transcription factor RAP2.2, has been reported to bind to PSY gene promoter site, thereby leading to an altered expression of the pigment . The genetic regulation of CRTISO gene is carried out by SDG8 (histone methyl transferase enzyme), responsible for methylation of chromatin linked with CRTISO gene. The absence of SDG8 leads to reduced gene expression and resultant decline in the biosynthesis of lutein and strigolactones . A CRTISO mutant ccr1, has been reported to downregulate more than 80 genes along with CRTISO gene. Another CRTISO mutant ccr2 was found to stimulate increased production of cis-carotenes in chromoplasts . In addition, metabolic feedback regulation is carried out by the enzymes DXS (for PSY) and LCYE (for CRTISO) respectively. This phenomenon has been observed in etiolated Arabidopsis seedlings where an elevated expression of PSY increased carotenoid levels due to DXS accumulation, which indicates metabolic feedback regulation triggered through PSY, which in turn enhanced the availability of MEP substrates .
Apart from enzymes, there are several environmental factors which are involved in regulation of carotenoid biosynthesis, among them, one of the crucial factors is light. Photoreceptors like PHY (phytochromes) are sensitive to red light and enhance the activity of PSY while CRY (cryptochromes) are sensitive to blue light and enhance the levels of pigments like chlorophyll and anthocyanin in leaves, as well as lycopene in fruits along with a decline in LCYB expression . In tomato, PHY as temperature sensors have been reported to affect plastid metabolism in the leaves and tomato fruit and the accretion of isoprenoid derived compounds. The studies on triple mutants phyAB1B2 (phytochrome silenced plants) demonstrated that the biosynthesis of the major carotenoid lycopene was found to be sensitive to PHY-temperature perception .
The light signaling is regulated positively by HY5 (elongated hypocotyls) and negatively by DDB1, DET1 and COP1 (constitutive photomorphogenic1) (see Fig. 4). The PIF1 (phytochrome interacting factor 1) regulates the signaling induced by light by functioning downstream and act as a negative regulator of phytochromes . Recently a self-shading model for regulation of carotenoid biosynthesis by PIF has been showcased. These investigators reported that in an unripe green fruit, when sunlight passes through its flesh, high levels of PIFs are maintained by a self-shading effect which in turn downregulate the initiation of carotenoid biosynthetic pathway and thus prevent carotenoid production. However, with the onset of chlorophyll degradation resulting in breakdown of PIFs the self-shading effect weakens thereby activating the carotenoid biosynthetic pathway as fruit ripening proceeds. These researchers also suggest strategies to manipulate this mechanism to obtain fruits enriched with carotenoids . Furthermore, exposure to UV (UV-B/C) radiations enhances the pigment concentration and the activity of genes encoding various enzymes involved in the biosynthesis pathway which imparts strength to the plant to survive in periods of stress .
In addition to the natural regulatory mechanism of the plant, selected carotenoid targeted regulation has been made possible by genetic engineering models to enhance the content of a specific carotenoid in the fruit. The biotechnological interventions for transgenic metabolic engineering, multigene engineering (gene scissor: CRISPR/cas9) and genetic breeding, in the last two decades have made it possible to enhance the productivity, nutritional adequacy and economic value of fruits  with enhanced carotenoids like lycopene , β-carotene  zeaxanthin, (enhanced to make up for 50% of the total carotenoid present in the fruit) , lutein and neoxanthin. The enhancement of these pigments (like β-carotene) initiates carotenoid biofortification, which can be further enhanced by downregulating the enzymes involved in carotenoid degeneration while enhancing carotenoid stability and retention .
Altered carotenoid chemistry in chromoplast to enhance stability
In horticultural crops, carotenoids accumulate in chromoplasts, which could vary from crystalline (carrot, papaya, tomato), globular (mango), fibrillary (pepper)  membranous (watermelon, mango, butternut squash), to reticulo-tubular based on sequestering structures in the chromoplasts . In addition, more than one type of chromoplasts can coexist in a particular species of fruit. The specific carotenoid accumulation is based on pigment-bearing substructures as seen in the case of red tomato and watermelon with carotenoid crystals resulting in huge accumulation of lycopene [135, 136] and β-carotene in carrot,  and orange cauliflower .
Several complex biochemical changes take place in the chromoplast leading to transformation of previously synthesized pigments and de novo biosynthesis of new pigments. In fruits, carotenoids are subjected to many chemical reactions like oxidation, epoxidation, (cis-trans) isomerization and cleavage of polyene chains. To increase the carotenoid accumulation in plant cells esterification is essential. Recently, several esterases XES (xanthophyll esterase) have been identified in plants [71, 139]. The esterification of violaxanthin and neoxanthin was found to be carried out by an XES homolog PYP1 (pale yellow petal 1) in tomato , while in wheat, XAT (xanthophyll acyl-transferase) catalyzed the esterification of lutein .
Carotenoids undergo esterification with fatty acids which makes them fat soluble and also facilitate their build up in chromoplast . The yellow xanthophylls are less stable due to their esterification by myristic and linoleic acid, which are unsaturated fatty acids. A pinacolic reordering of the epoxy-cyclohexenyl groups in the chromoplast membranes converts epoxy-xanthophylls, like violaxanthin and antheraxanthin, into keto-xanthophylls like capsanthin, capsorubin and cryptocapsin .
In contrast to yellow xanthophylls, the red xanthophylls like capsanthin and capsorubin, found in ripe pepper fruit, demonstrate more stability owing to their esterification by lauric and palmitic acid which are short chain fatty acids. The augmented carotenoid stability by esterification could aid in biofortification and thus be explored in depth by future research projects . In addition, the report on the cloning of the pepper enzyme, CCS (capsanthin/capsorubin)  and its promoter , provides a model to alter the biosynthesis and metabolism of cyclic carotenoids in chromoplasts of pepper fruits and the re-engineering of carotenoid biosynthesis in other carotenoid accumulating fruit.
The chemical changes in the chloroplast lead to the accumulation of keto-carotenoids with changes in metabolism of lipids as galactolipids levels have been found to diminish while phospholipids have been reported to accumulate in chromoplasts. Oxygenated configurations of carotenoids having acylcyclopentanol end groups like capsanthin, capsanthin-5,6-epoxide and capsorubin have been observed to control the intensity of red color in chili pepper fruits . In ripened pepper fruits, ketoxanthophylls (capsanthin, capsorubin and capsolutein) accumulate the most, followed by xanthophylls (violaxanthin and zeaxanthin) then the epoxyxanthophylls (capsanthin-3,6 epoxide and capsanthin-5,6-epoxide) along with a small accumulation of lycopene. Due to several chemical reactions in the chromoplast, many novel carotenoids have been detected in ripened paprika fruits like 3′-deoxy-capsanthin and 3,4-dehydroxy-3′-deoxycapsanthin .
Carotenoid metabolism and storage in fruit ripening
The ripening of the tomato fruit has been investigated recently for the coordinated regulation of the genes involved, chromatin, epigenetics, transcriptomics, post translational and at the level of protein expression. These investigators have reported that the non-coding RNAs play a crucial regulatory role in fruit ripening at transcriptional and post transcriptional levels (for details see review ).
The final concentration of carotenoids in plant tissues is dependent upon the enzymes; lipoxygenases, and CCDs (carotenoid cleavage dioxygenases) involved in degradation and cleavage. In Arabidopsis four CCD genes namely CCD1, CCD4, CCD7 and CCD8 and five NCEDs (9-cis epoxy carotenoid dioxygenases) namely NCED2, NCED3, NCED5, NCED6 and NCED9 have been identified [44, 149]. Many trials on fruits report that the carotenoid content in fruits and the expression of CCD1 and CCD4 are inversely proportional to each other . Also, while CCD1 is closely related to production of volatile compounds like aroma in fruits, CCD7 and CCD8 play a vital role in strigolactones production [151,152,153] and the NCED family plays a major role in production of the growth hormone ABA .
CCDs cleave the carotenoids into apocarotenoids and majority of them like, bixin, saffron, crocin, apocarotenals, apolycopenoides, ionones (i.e., β-ionone), peridinin and many more have been reported as bioactive compounds with therapeutic efficacy and industrial applications [44, 155,156,157,158,159]. CCDs play an important regulatory role and impact the final content of carotenoids and the presence of volatile compounds which affect flavor and aroma. For example, β-carotene, the precursor of retinal (Vitamin A), is the immediate precursor of one of the most important flavor volatiles, β-ionone . In tomato, two enzymes, CCD1A and CCD1B, that can cleave multiple carotenoid substrates to generate geranylacetone, pseudoionone, and β-ionone have been identified [161,162,163]. CCD’s have also been reported to have a role in controlling the fruit color. In peach, a mutations in PpCCD4 attenuates its levels resulting in yellow flesh variety due to truncated protein with reduced carotenoid degradation activity [164, 165].
In citrus fruits (Citrus unshiu), cleavage of β-cryptoxanthin and zeaxanthin by CitCCD4 results in the formation of β-citraurin, which is responsible for the reddish color in the peel. The production of C30 apocarotenoid in orange has been linked to CCD4b, thereby influencing the carotenoid accumulation in citrus fruits [166, 167].
Chromoplasts act as metabolic sinks to sequester the biosynthesized carotenoids into carotenoid-lipoprotein structures such as fibrils and plastoglobules . These structures help to accumulate carotenoids and prevent overloading and inhibition of carotenoid synthesis . The variability in these structures is linked to the variations of carotenoid profile in various fruits therefore governing these structures would directly influence carotenoid accumulation. The carotenoid associated proteins, fibrillin in pepper and its orthologue, carotenoid-associated protein (CHRC) in cucumber  play an important role in the production of carotenoid-lipoprotein structures . In tomato, fibrillin overexpression has resulted in enhanced carotenoids and volatiles production .
Carotenoids are produced in various plastids but accumulate in chromoplast at high levels resulting in attractive hues of fruits thereby the regulation of chromoplast biogenesis has a strong impact on the carotenoid biosynthesis and accumulation. At the molecular level the Or (Orange) gene has been reported to initiate biogenesis of chromoplasts, as its mutants have been reported to initiate non colored plastid differentiation into chromoplasts with an augmented ability to amass β-carotene in potato, cauliflower  and melon . Recent developments in RNA-Sequence transcriptomic profiling and microscopic analysis revealed the impact of overexpression Or gene resulting in augmented chromoplast size in very young fruits, promoted flower and fruit development, enhanced ethylene production, expression of ripening associated genes a . Thus, Or gene has been a much sought-after target for nutritional biofortification and alteration of horticultural traits in agricultural products [44, 173, 174]. The modification of Or gene by genome editing has been proposed to manipulate carotenoid biosynthetic pathway, thereby making use of its interaction with PSY resulting in enhanced sequestering, protection from degradation and improved plants tolerance to abiotic stress .
Furthermore, the activity and accumulation of biosynthetic enzymes such as PSY was found to be regulated by chaperones Or and Hsp70 in liaison with the Clp protease complex in the stroma, thereby suggesting that different chaperone families target distinct processes with regard to carotenoid accumulation and metabolism in fruit ripening . Several biotechnological tools have been implemented to alter and enrich the plant tissues with carotenoids (see [44, 82]). However, most of these strategies have been focused on manipulating carotenoid biosynthesis and metabolism. Recently enhancement of carotenoid sink capacity in plastids by supporting the differentiation of carotenoid sequestering structures in plant tissues has gained much importance. The, over-expression of the Or protein, for example, promotes the formation of carotenoid-sequestering plastoglobuli in transgenic corn  and a 2-fold increases in carotenoids in transgenic cassava [44, 177]. Supporting evidence for the manipulation of deposition structures comes from work carried out by Simkin et al. . The over-expression of the fibrillin protein in tomato resulted in an increase plastoglobuli number, and an increase in β-carotene (+ 64%) and lycopene (+ 118%) . These authors also demonstrated that this increased pool of carotenoids resulted in a 36 and 74% increase in the β-carotene derived volatiles β-ionone and β-cyclocitral respectively and a 50 and 122% increase in the lycopene derived volatiles citral and 6-methyl-5-hepten-2-one respectively .
Furthermore, the transfer of carotenoid biosynthesis to the cytosol can be brought about by the activity of crtB in plastids and its combination with cytosolic bacterial enzymes to produce carotenoids in extraplastidial sites [178, 179] and accumulation of lycopene in the cytosol of tobacco . The isoprenoid precursors are transferred to the cytosol via the MVA (mevalonic acid) pathway. These strategies have opened novel approaches for carotenoid biofortification and thus creating more space for carotenoids in plants (for details see reviews [174, 180]).
Anthocyanin biosynthesis: enhances flavonoid content of ripened fruits
There are numerous examples of fruits and vegetables like pomegranate, cherry, plums, turnip, blackberries, blueberries, strawberries, red pears, onions, red cabbage, red apples, prunes, eggplant, cranberries and grapes which accumulate anthocyanin when ripe and change from green to purple or red . Fruits exhibit varied pigmentation of anthocyanins in flesh and/or skin. As ripening proceeds, anthocyanin biosynthesis is triggered in some fruits post chlorophyll and carotenoid degradation . In a trial on pomegranate, the development of red color was reported with an increase in anthocyanin pigment and degradation of chlorophylls and carotenoids. The major anthocyanins reported in the pomegranate (Punica granatum L.) peel were cyanidin 3,5-diglucoside and cyanidin-3-O-glucoside respectively . Also, in ripened avocado (Persea americana Mill.), color changes from green to purple to black have been attributed to a fall in chlorophyll and an increase in glycosylated anthocyanin; cyanidin 3-O-glucoside . The anthocyanins cyanidin-3-rutinoside and cyanidin-3-glucoside were also reported for ripening induced color changes in cherries (Prunus avium) . The biosynthesis of anthocyanin is regulated by multiple factors like hormonal, genetic and environmental (see Fig. 5). An in-depth study of these regulatory factors involved in anthocyanin biosynthesis highlight the pathways for biotechnological editing to enhance pigment content. R2R3MYB, BASIC HELIX-LOOP HELIX (bHLH), WD40 COMPLEX are the three main TFs regulating the structural genes of anthocyanin biosynthesis at an individual level and as a team as MBW complex. In a recent analysis RrMyb10 was reported as the anthocyanin inducer in Ribes species, and its role in manipulating anthocyanin biosynthesis in heterologous systems has been highlighted . Also, recent comparative analysis and genome-wide identification of MYB TFs in two varieties of banana, Musa acuminata and Musa balbisiana would enable future prospects for functional studies . Apart from these, SEPALLATA and SQUAMOSA class MADS BOX genes also regulate anthocyanin accumulation in fruits. In addition, anthocyanin biosynthesis can also be triggered by sucrose signaling by inducing production of PAP1 (anthocyanin pigment1)  along with the support of the plant growth hormones. Among the plant growth hormones, ABA and jasmonic acid act synergistically with sucrose signaling while gibberellin has been found to inhibit sucrose signaling . Though ethylene signaling has been reported to enhance anthocyanin biosynthesis in several trials [190, 191], however, in Arabidopsis, ethylene inhibits anthocyanin accumulation which is induced by sugar and photosynthesis by curbing the activity of TFs positively involved in regulation of MYB-bHLH-WD40 and increasing the expression of MYBL2 (a negative R3-MYB regulator) along with down regulation of SUC1 (sucrose transporter 1), PAP1, TT8 and GL3 . In addition, auxins have also been reported to regulate anthocyanin biosynthesis in a negative manner [193, 194]. The role of ABA has been reported in a number of trials as a positive regulator of anthocyanin synthesis . Silencing of key ABA biosynthetic gene FaNCED1 and LbNCED1 resulted in minimal anthocyanin production in strawberries and lyceum plants . Among the non-climacteric fruits, strawberry has been considered as a model fruit to study ripening related characteristics, wherein both sucrose and ABA are involved in signaling anthocyanin biosynthesis. However, a recent trial on bilberry (Vaccinium myrtillus L.) (non-climacteric fruit) demonstrated that treatment of unripe bilberry fruits (attached/detached from the plant) with ABA resulted in anthocyanin accumulation and cell wall modification while the sucrose treatment of unripe bilberry fruits did not promote anthocyanin biosynthesis. Therefore, these results indicate that regulation of fruit ripening, is fruit specific and would differ from one fruit to the other .
Manipulation of both the functional genes and the TFs involved in regulating anthocyanin biosynthesis have been found to enhance the flavonoid content. The silencing of DET1 gene has resulted in reformed developmental processes mediated by light and an augmented flavonoid content . Also, the flavonoid content of the tomato peel has been reported to be increased by 78 fold by overexpressing chalcone isomerase (CHI) gene in tomatoes . However, the expression of two snapdragon genes Ros1 and Del which encode MYB and bHLH resulted in the most substantial increase in anthocyanin content leading to development of fully purple hue on tomato fruits . In addition, crossing the Del/Ros1 lines with overexpressing lines of AtMYB12 resulted in enhanced accumulation of anthocyanin . Furthermore, the anthocyanin accumulation genes Del and Ros1 were recently transferred from transgenic Micro-tom to Moneymaker tomato cultivar via traditional breeding. The anthocyanin content in the inbred fruit enriched with anthocyanin was escalated to about 131% of the parent level, phenolic compounds upsurged by 51% coupled with an augmented antioxidant activity and reduced growth of bacteria . Recently, in tomato, SlMYB75 has been reported to be effective in inducing anthocyanin accumulation at the rate of 1.86 mg/g in varied tissues, coupled with an increase in production of ethylene,flavonoid, phenolic compounds, and aroma . Therefore, targeting of specific TFs could engineer anthocyanin accumulation in a ripened fruit and thereby enhance its nutraceutical and industrial potential.
Response of anthocyanins to stimuli suggests ways to enhance its production
Anthocyanins have been termed as “chameleons” or the “color diversity hub” due to frequent changes in expression of color related to biotic or abiotic factors like a drop-in temperature, brininess, dearth of nitrogen and minerals like phosphorous which are generally expressed as purple coloration on stem, leaves and other parts of the plant as response to low light stress. Anthocyanins display changes in tones due to environmental factors . The soil pH affects the pH of cellular compartments thereby affecting the subcellular concentration of flavonoids and expression of pigments ranging from red to blue. Fertilizers rich in nitrogen have been reported as negative regulators resulting in a fall in PAP1 and TT8 proteins from WD40-bHLH-MYB complex, while they enhance the formation of negative regulators like LBD37/38/39 . The role of temperature and light on anthocyanin accumulation has been well studied. In a trial on grapevine berries, changes in temperature varied the expression of the MYB genes (VlMYBA2, VlMYBA1–2, VlMYBA1–3) related to anthocyanin biosynthesis. The maximum anthocyanin levels were observed at 15 °C in light treatment as compared to a fall in anthocyanin at 35 °C in dark . A positive correlation between exposure to sunlight and anthocyanin content was also studied on Litchi Chinensis which identified an R2R3-MYBTF encoding gene; LCMYB1 whose expression enhanced on exposure to ABA and sunlight. The expression of this gene also correlated with tissue anthocyanin content and expression of LCUFGT gene . The molecular switch of light signaled processes in plant is COP1 which is a negative regulator of photoreceptors and mediates TFs which promote photomorphogenesis by Ub- proteasome system. Moreover, in apples higher levels of MdMYB1 accumulate on exposure to light following which it interacts with MdCOP1 . The protein is degraded by ubiquitin dependent pathway in dark as COP1 interacts with target TFs like HY5 and it regulates their breakdown and degradation via the 26S proteasome pathway . In Arabidopsis, HY5 has been observed to activate CHS (chalcone synthase) gene and promote flavonoid build up as a response to stimulus like light and UV-B radiation. Recent reports suggest the role of UV-B induced accretion of anthocyanins through the COP1 regulated signaling in binding of HY5 to MYB gene promoters . The exposure of UV radiation on the fruit affects the anthocyanin accumulation depending on its stage of development. The shikimate pathway genes have been reported to be upregulated by UV-A radiations in 3 weeks old grape berries as compared to UV-B and UV-C radiations which positively regulated the shikimate pathway genes by 11 weeks . UV radiation has been reported to have similar upregulation of structural genes VvANR, VvLAR1, VvLAR2 and regulatory genes MYB5a, MYB5b, MYBPA1 in grapes . In the dessert plant Reaumuria soongorica, the expression of flavanone-3-hydroxylase, an enzyme involved in anthocyanin biosynthesis increased under the influence of UV radiations and stress due to drought . The effect of mutations on anthocyanin accumulation has been studied well in the strawberry fruit. The red color of strawberry is due to the vacuole accumulated anthocyanins. In a wild variety of strawberry (Fragaria vesca) with white color fruits, a mutant RAP (reduced anthocyanin in petioles) has been reported. This mutation was a stop codon in the synthesis of GST (glutathione s-transferase) gene. Among the eight genes in GST family, RAP is present abundantly in ripening fruits and acts as a transporter of anthocyanin. However, in cultivated strawberry, RAP mutant acts downstream to FvMYB10 which is the fruit specific TFs and results in a reduction in fruit color . Therefore, a knowledge of the impact of various environmental stimuli on TFs involved in anthocyanin biosynthesis could be utilized to engineer anthocyanin production and enhance its accumulation as an essential nutraceutical in a ripened fruit.
Structural modifications impart stability to anthocyanins
Several anthocyanins have been isolated from plant species based on a single basic flavonoid framework of carbon atoms as C6-C3-C6. The basic flavonoid structure contains one integrated aromatic ring as A ring, the B ring which is a phenyl component and the C ring comprises of a heterocyclic benzopyran . The stability of color in anthocyanins is dependent on the structural modifications of the B ring. It has been reported that hydroxylation of the B ring imparts a blue hue while methylation imparts a red hue to anthocyanidins. Malvidin has been reported as the reddest anthocyanin . Cyanidin, delphinidin and petunidin are more sensitive to oxidation owing to the presence of O-diphenol structure as compared to malvidin and peonidin which do not possess the hydroxyl groups at the ortho position . The accumulation of anthocyanins in fruits is accompanied by an immediate modification by glycosylation, methylation, and acylation to increase their stability as vacuolar anthocyanins. In grapes, the linkage of glucose molecules to the anthocyanic structure can only be at the C3 position to form monoglycosidic anthocyanins, however, in other plants the linkage of glucose molecule can be at both C3 and C5 positions to form diglycosidic anthocyanins . Though the stability of monoglucosidic anthocyanins is lesser than diglucosidic counterparts, monoglucosidic anthocyanins have more deeper color. In grapes, the principal anthocyanins reported are monoglucosides of delphinidin, peonidin, malvidin, cyanidin, petunidin and pelargonidin. Yet another structural alteration of the B ring in anthocyanins is carried out by methylation of the hydroxyl groups at the C3 or C5 positions. In grapes, divalent cation dependent OMT (O-methyl transferase) have been reported to regulate the process of methylation of flavanols and anthocyanins by preferring the 3rd and 5th position for methylation with substrates having hydroxyl groups at 3rd,4th and 5th position thus playing a vital role in anthocyanin biosynthesis . Furthermore, the acylation of the sugar at the C6 position of glucose moiety with inclusion of aromatic and aliphatic functional groups can promote the chemical stability and increase structural diversity of anthocyanins. In addition to coumaric acid two stereoisomers of anthocyanidin coumaryl glucosides have been reported in grapes . Some complex mechanisms like self-association, co-pigmentation, and creation of pyranoanthocyanins impart stability to the color of anthocyanins. Pyranoanthocyanins are formed during the process of fermentation or in oxygenation processes which are controlled. One of the members of this family of pyranoanthocyanins is vitisin A, which is formed as a by-product of reaction between pyruvic acid and anthocyanins (cyanidin, delphinidin, peonidin, petunidin, malvidin) bearing either glycosyl, acetyl glycosyl or coumaroyl glycosyl groups and it has been reported to play an important role as an intermediate in alcohol fermentation. Another example of pyranoanthocyanins is vitisin B, reported as the primary product of ethanol oxidation and is formed by a chemical reaction between acetaldehyde and malvidin possessing either glycosyl, acetyl glycosyl or coumaroyl glycosyl groups .
Transport and storage of anthocyanins
Anthocyanin synthesis takes place at endoplasmic reticulum following which they are transported to the anthocyanic vacuolar inclusions for storage. Electron microscopy of plant cells exhibiting anthocyanin pigments depict anthocyanic vacuolar inclusions (AVI) which are formed because of hydrogen bonding of anthocyanin to the protein matrix. The concentration of anthocyanins have been reported to be intensified in areas rich in AVI . These vacuoles are formed by acylated anthocyanins and glycosylation of the acylated anthocyanins reduces their tendency to form AVI . There are many regulatory systems which mediate anthocyanin transport in plants like MATE (multidrug and toxic extrusion), GSTs, allergen Fra a 1 and ABC (ATP-binding cassette) proteins [223, 224]. Among the other transporters, GSTs play a crucial role, as a decline in their activity results in visual pigment loss resulting in phenotypes like bz2 (Bronze-2) in maize, an9 (anthocyanin 9) in petunia and tt19 (transparent testa 19) in Arabidopsis . Several studies have reported the role of tt19 protein as a carrier for seclusion and transport of anthocyanins into the vacuole from the cytosol . GST’s have also been identified in fruit and flower pigmentation like LcGST4 in lychee  Riant in peach  and MdGST in apple .
Mutual exclusion of pigments with anthocyanins
Anthocyanins exhibit a property of co-pigmentation which leads to stabilization of color in plants. The co-pigments can be of a wide range from alkaloids, other flavonoids, nucleotides, organic acids, and metals. The complexes thus formed result in increased absorption intensity and change in wavelength leading to increased hue intensity of anthocyanins . Many factors influence the magnitude of co-pigmentation like structure, concentration of the anthocyanin and their co-pigment, the solidity of ionic bonding and their molar ratio, temperature and pH . While carotenoids and anthocyanins coexist, a mutual exclusion has been reported for betalains and anthocyanins. An interesting observation is the absence of anthocyanin from any betalain cumulating family. It has been reported that the plants accumulating betalains do express a few flavonoid biosynthetic enzymes and accumulate flavanols, however the final step regulated by ANS of the flavonoid pathway is not carried out due to the presence of truncated ANS enzyme in plants which cannot cumulate betalain .
Considering the importance of pigments in nutraceuticals and varied industries and their accumulation across different developmental stages of ripening, decisions regarding the optimum time for harvest could be made based on the pigments desired. Harvesting of un-ripened fruits could be a potential source of nutraceuticals like chlorophylls’ and xanthophylls’, the breaker stage would contribute to a supply of both chlorophyll and carotenoids, while fully ripened fruits will be a reservoir of pigments like anthocyanins and carotenoids along with their cleavage products, many of which have important clinical functions [39, 44, 158, 159, 233,234,235]. Many non-invasive techniques could be used to determine the type and quantity of pigments at different stages of ripening  ranging from the age-old colorimeters  to the more recent electronic nose technique . The other commonly used light transmittance techniques are visible imaging , visible and infrared spectroscopy (VNIR) spectroscopy , multispectral and fluorescence imaging , CT and MRI scan . Utilizing the visual signals of fruit ripening in terms of color, indicative of pigment accumulation, the desired pigments could be harvested and processed at an individual level based on its bioactivity. Recent evidence indicates that the regulatory mechanism involved in expression of ripening related genes are more complex than imagined earlier. To further fine tune the expression of pigments in fruits, post-transcriptional mechanisms along with RNA splicing would play the key role and offer novel substrate for the upsurge of genetic variables and grant an evolutionary flexibility to the expression of fruit pigments .
Also, extensive research on pigment biosynthetic pathways, stability, degradation, storage, and the underlying regulatory mechanisms highlights ways to engineer pigment content with the aid of biotechnological advances and genome editing . Denovo domestication via molecular breeding using CRISPR/Cas9 genome engineering strategy has promoted an increase in pigment content such as lycopene by 500% in engineered lines in comparison to wild tomato varieties . Manipulating the biosynthesis and stockage of secondary metabolites also adds the potential of improving the nutritional and health benefits, flavors and aromas of fruits and vegetables that has the potentially to encourage a more diverse and healthy diet . Plant secondary metabolites and their breakdown products have a high degree of pharmaceutical potential, which is still largely unexplored. Many have been reported to have anti-cancer and anti-inflammatory properties and can be used to treat mental health. Saffron, for example, (30 mg/day− 1) is used to treat mild to moderate depression with no side effects . These data only strengths the view that increasing the content of these clinically relevant compounds in foods could potentially have a wide impact on human health.
Some of these compounds have also been used as biopesticides and bioherbicides making them a potential source of alternate farming compounds that could be used to reduce our needs on chemicals that may be harmful to the environment, wildlife, and insect populations. Increasing their content and marketable yield either through breeding, selective harvesting or genetic engineering could reduce the overall costs, making them more attractive alternatives to current use chemicals.
Another opportunity to potentially manipulate fruit metabolite content is to manipulate primary metabolism [246, 247] directly in the fruit. Several authors have suggested that fruit carry out carbon capture, either directly through stomata on their surface, or through the recycling of respiratory carbon via the Calvin-Benson cycle [10, 78,79,80,81].
This review generates new hypothesis for future research as different stages of ripening induce several structural changes in pigments resulting in the formulation of novel unexplored pigments, which may prove to be a boost to the existing era of green technology.
Availability of data and materials
Yahia EM, García-Solís P, Celis MEM. Contribution of fruits and vegetables to human nutrition and health. In: Postharvest physiology and biochemistry of fruits and vegetables: Elsevier; 2019. p. 19–45.
Karasawa MMG, Mohan C. Fruits as prospective reserves of bioactive compounds: a review. Nat Prod Bioprospect. 2018;8(5):335–46.
Nasri H, Baradaran A, Shirzad H, Rafieian-Kopaei M. New concepts in nutraceuticals as alternative for pharmaceuticals. Int J Prev Med. 2014;5(12):1487.
Wildman RE. Handbook of nutraceuticals and functional foods: CRC press; 2016.
Bhatt ID, Rawat S, Badhani A, Rawal RS. Nutraceutical potential of selected wild edible fruits of the Indian Himalayan region. Food Chem. 2017;215:84–91.
Wrolstad RE, Culver CA. Alternatives to those artificial FD&C food colorants. Annu Rev Food Sci Technol. 2012;3:59–77.
Belwal T, Pandey A, Bhatt ID, Rawal RS, Luo Z. Trends of polyphenolics and anthocyanins accumulation along ripening stages of wild edible fruits of Indian Himalayan region. Sci Rep. 2019;9(1):1–11.
Solovchenko A, Yahia EM, Chen C. Chapter 11 - Pigments. In: Yahia EM, editor. Postharvest Physiology and Biochemistry of Fruits and Vegetables: Woodhead Publishing; 2019. p. 225–52.
Gonzali S, Perata P. Fruit colour and novel mechanisms of genetic regulation of pigment production in tomato fruits. Horticulturae. 2021;7(8):259.
Simkin AJ, Faralli M, Ramamoorthy S, Lawson T. Photosynthesis in non-foliar tissues: implications for yield. Plant J. 2020;101(4):1001–15.
Croce R, Van Amerongen H. Natural strategies for photosynthetic light harvesting. Nat Chem Biol. 2014;10(7):492.
Tanaka A, Fujita K, Kikuchi K. Nutrio-physiological studies on the tomato plant. Soil Sci Plant Nutr. 1974;20(1):57–68.
Hetherington SE, Smillie RM, Davies WJ. Photosynthetic activities of vegetative and fruiting tissues of tomato. J Exp Bot. 1998;49(324):1173–81.
Obiadalla-Ali H, Fernie AR, Lytovchenko A, Kossmann J, Lloyd JR. Inhibition of chloroplastic fructose 1,6-bisphosphatase in tomato fruits leads to decreased fruit size, but only small changes in carbohydrate metabolism. Planta. 2004;219(3):533–40.
Fernández-Marín B, García-Plazaola JI, Hernández A, Esteban R. Plant photosynthetic pigments: methods and tricks for correct quantification and identification. In: Advances in plant ecophysiology techniques. Cahm: Springer; 2018. p. 29–50.
Kim J, DellaPenna D. Defining the primary route for lutein synthesis in plants: the role of Arabidopsis carotenoid beta-ring hydroxylase CYP97A3. Proc Natl Acad Sci. 2006;103(9):3474–9.
Wang K, Tu W, Liu C, Rao Y, Gao Z, Yang C. 9-cis-neoxanthin in light harvesting complexes of photosystem II regulates the binding of violaxanthin and xanthophyll cycle. Plant Physiol. 2017;174(1):86–96.
Hashimoto H, Uragami C, Cogdell RJ. Carotenoids and photosynthesis. In: Carotenoids in Nature: Springer; 2016. p. 111–39.
Gul K, Tak A, Singh A, Singh P, Yousuf B, Wani AA. Chemistry, encapsulation, and health benefits of β-carotene-a review. Cogent Food Agric. 2015;1(1):1018696.
Noviendri D, Hasrini RF, Octavianti F. Carotenoids: sources, medicinal properties and their application in food and nutraceutical industry. J Med Plants Res. 2011;5(33):7119–31.
Przybylska S. Lycopene – a bioactive carotenoid offering multiple health benefits: a review. Int J Food Sci Technol. 2020;55(1):11–32.
Thies F, Mills LM, Moir S, Masson LF. Cardiovascular benefits of lycopene: fantasy or reality? Proc Nutr Soc. 2017;76(2):122–9.
Palozza P, Parrone N, Catalano A, Simone R. Tomato lycopene and inflammatory cascade: basic interactions and clinical implications. Curr Med Chem. 2010;17(23):2547–63.
Johnson EJ. Role of lutein and zeaxanthin in visual and cognitive function throughout the lifespan. Nutr Rev. 2014;72(9):605–12.
Bernstein PS, Li B, Vachali PP, Gorusupudi A, Shyam R, Henriksen BS, et al. Lutein, zeaxanthin, and meso-zeaxanthin: the basic and clinical science underlying carotenoid-based nutritional interventions against ocular disease. Prog Retin Eye Res. 2016;50:34–66.
Rivera-Madrid R, Aguilar-Espinosa M, Cárdenas-Conejo Y, Garza-Caligaris LE. Carotenoid derivates in achiote (Bixa orellana) seeds: synthesis and health promoting properties. Front Plant Sci. 2016;7:1406.
Roehrs M, Figueiredo CG, Zanchi MM, Bochi GV, Moresco RN, Quatrin A, et al. Bixin and norbixin have opposite effects on glycemia, lipidemia, and oxidative stress in streptozotocin-induced diabetic rats. Int J Endocrinol. 2014;2014:839095.
Korani S, Korani M, Sathyapalan T, Sahebkar A. Therapeutic effects of Crocin in autoimmune diseases: a review. Biofactors. 2019;45(6):835–43.
Alavizadeh SH, Hosseinzadeh H. Bioactivity assessment and toxicity of crocin: a comprehensive review. Food Chem Toxicol. 2014;64:65–80.
Basu A, Rhone M, Lyons TJ. Berries: emerging impact on cardiovascular health. Nutr Rev. 2010;68(3):168–77.
Faria A, Pestana D, Teixeira D, de Freitas V, Mateus N, Calhau C. Blueberry anthocyanins and pyruvic acid adducts: anticancer properties in breast cancer cell lines. Phytother Res. 2010;24(12):1862–9.
Lin BW, Gong CC, Song HF, Cui YY. Effects of anthocyanins on the prevention and treatment of cancer. Br J Pharmacol. 2017;174(11):1226–43.
İnanç AL. Chlorophyll: structural properties, Health Benefits and Its Occurrence in Virgin Olive Oils. Acad Food J/Akademik GIDA. 2011;9(2):26–32.
Vivek P, Prabhakaran S, Shankar SR. Assessment of nutritional value in selected edible greens based on the chlorophyll content in leaves. Res Plant Biol. 2013;3(5):45–9.
Gengatharan A, Dykes GA, Choo WS. Betalains: natural plant pigments with potential application in functional foods. LWT-Food Sci Technol. 2015;64(2):645–9.
Khan MI. Plant betalains: safety, antioxidant activity, clinical efficacy, and bioavailability. Compr Rev Food Sci Food Saf. 2016;15(2):316–30.
Fu Y, Shi J, Xie S-Y, Zhang T-Y, Soladoye OP, Aluko RE. Red beetroot Betalains: perspectives on extraction, processing, and potential health benefits. J Agric Food Chem. 2020;68(42):11595–611.
Rodriguez-Amaya DB. Update on natural food pigments-a mini-review on carotenoids, anthocyanins, and betalains. Food Res Int. 2019;124:200–5.
Ansari M, Ansari S. Lycopene and prostate cancer. Future Oncol. 2005;1(3):425–30.
Rafi MM, Kanakasabai S, Gokarn SV, Krueger EG, Bright JJ. Dietary lutein modulates growth and survival genes in prostate Cancer cells. J Med Food. 2015;18(2):173–81.
Kotake-Nara E, Kushiro M, Zhang H, Sugawara T, Miyashita K, Nagao A. Carotenoids affect proliferation of human prostate cancer cells. J Nutr. 2001;131(12):3303–6.
Liu X, Song M, Gao Z, Cai X, Dixon W, Chen X, et al. Stereoisomers of Astaxanthin inhibit human Colon Cancer cell growth by inducing G2/M cell cycle arrest and apoptosis. J Agric Food Chem. 2016;64(41):7750–9.
Shareck M, Rousseau M-C, Koushik A, Siemiatycki J, Parent M-E. Inverse Association between Dietary Intake of Selected Carotenoids and Vitamin C and Risk of Lung Cancer. Front Oncol. 2017;7:23.
Simkin AJ. Carotenoids and Apocarotenoids in planta: their role in plant development, contribution to the flavour and aroma of fruits and flowers, and their nutraceutical benefits. Plants. 2021;10(11):2321.
Tay-Agbozo S, Street S, Kispert L. The carotenoid Bixin found to exhibit the highest measured carotenoid oxidation potential to date consistent with its practical protective use in cosmetics, drugs and food. J Photochem Photobiol B Biol. 2018;186:1–8.
Tibodeau JD, Isham CR, Bible KC. Annatto constituent cis-bixin has selective antimyeloma effects mediated by oxidative stress and associated with inhibition of thioredoxin and thioredoxin reductase. Antioxid Redox Signal. 2010;13(7):987–97.
Yu Y, Wu DM, Li J, Deng SH, Liu T, Zhang T, et al. Bixin attenuates experimental autoimmune encephalomyelitis by suppressing TXNIP/NLRP3 Inflammasome activity and activating NRF2 signaling. Front Immunol. 2020;11:593368.
W-y H, H-c Z, W-x L, C-y L. Survey of antioxidant capacity and phenolic composition of blueberry, blackberry, and strawberry in Nanjing. J Zhejiang Univ Sci B. 2012;13(2):94–102.
Siva R. Status of natural dyes and dye-yielding plants in India. Curr Sci. 2007;92(7):916–25.
Fraser PD, Enfissi EMA, Goodfellow M, Eguchi T, Bramley PM. Metabolite profiling of plant carotenoids using the matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Plant J. 2007;49(3):552–64.
Burns J, Fraser PD, Bramley PM. Identification and quantification of carotenoids, tocopherols and chlorophylls in commonly consumed fruits and vegetables. Phytochemistry. 2003;62(6):939–47.
Poojary MM, Passamonti P. Optimization of extraction of high purity all-trans-lycopene from tomato pulp waste. Food Chem. 2015;188:84–91.
Chuyen HV, Roach PD, Golding JB, Parks SE, Nguyen MH. Optimisation of extraction conditions for recovering carotenoids and antioxidant capacity from Gac peel using response surface methodology. Int J Food Sci Technol. 2017;52(4):972–80.
Zaghdoudi K, Pontvianne S, Framboisier X, Achard M, Kudaibergenova R, Ayadi-Trabelsi M, et al. Accelerated solvent extraction of carotenoids from: Tunisian Kaki (Diospyros kaki L.), peach (Prunus persica L.) and apricot (Prunus armeniaca L.). Food Chem. 2015;184:131–9.
Hiranvarachat B, Devahastin S. Enhancement of microwave-assisted extraction via intermittent radiation: extraction of carotenoids from carrot peels. J Food Eng. 2014;126:17–26.
Strati IF, Gogou E, Oreopoulou V. Enzyme and high pressure assisted extraction of carotenoids from tomato waste. Food Bioprod Process. 2015;94:668–74.
Goula AM, Ververi M, Adamopoulou A, Kaderides K. Green ultrasound-assisted extraction of carotenoids from pomegranate wastes using vegetable oils. Ultrason Sonochem. 2017;34:821–30.
Oliveira J, Alhinho da Silva M, Nr T, De Freitas V, Salas E. Screening of anthocyanins and anthocyanin-derived pigments in red wine grape pomace using LC-DAD/MS and MALDI-TOF techniques. J Agric Food Chem. 2015;63(35):7636–44.
Norhaslinda R, Noratiqah JM, Amin BA, RMA K. Quantitative and optimization of anthocyanin extracted from pomegranate (Punica granatum) extract by high-performance liquid chromatography (HPLC). Pharmacogn J. 2018;10(4):650–3.
Wang W, Jung J, Tomasino E, Zhao Y. Optimization of solvent and ultrasound-assisted extraction for different anthocyanin rich fruit and their effects on anthocyanin compositions. LWT-Food Sci Technol. 2016;72:229–38.
Maran JP, Sivakumar V, Thirugnanasambandham K, Sridhar R. Extraction of natural anthocyanin and colors from pulp of jamun fruit. J Food Sci Technol. 2015;52(6):3617–26.
Backes E, Pereira C, Barros L, Prieto M, Genena AK, Barreiro MF, et al. Recovery of bioactive anthocyanin pigments from Ficus carica L. peel by heat, microwave, and ultrasound based extraction techniques. Food Res Int. 2018;113:197–209.
Machado APDF, Pasquel-Reátegui JL, Barbero GF, Martínez J. Pressurized liquid extraction of bioactive compounds from blackberry (Rubus fruticosus L.) residues: a comparison with conventional methods. Food Res Int. 2015;77:675–83.
Calvano CD, Ventura G, Cataldi TR, Palmisano F. Improvement of chlorophyll identification in foodstuffs by MALDI ToF/ToF mass spectrometry using 1, 5-diaminonaphthalene electron transfer secondary reaction matrix. Anal Bioanal Chem. 2015;407(21):6369–79.
Das A, Guyer L, Hörtensteiner S. Chlorophyll and chlorophyll catabolite analysis by HPLC. In: Plant Senescence: Springer; 2018. p. 223–35.
Zhang Z-H, Wang L-H, Zeng X-A, Han Z, Wang M-S. Effect of pulsed electric fields (PEFs) on the pigments extracted from spinach (Spinacia oleracea L.). Innovative Food Sci Emerg Technol. 2017;43:26–34.
Özkan G, Bilek SE. Enzyme-assisted extraction of stabilized chlorophyll from spinach. Food Chem. 2015;176:152–7.
Wang R, Angenent GC, Seymour G, de Maagd RA. Revisiting the role of master regulators in tomato ripening. Trends Plant Sci. 2020;25(3):291–301.
Mukherjee S. Recent advancements in the mechanism of nitric oxide signaling associated with hydrogen sulfide and melatonin crosstalk during ethylene-induced fruit ripening in plants. Nitric Oxide. 2019;82:25–34.
Durán-Soria S, Pott DM, Osorio S, Vallarino JG. Sugar signaling during fruit ripening. Front Plant Sci. 2020;11:564917.
Berry HM, Rickett DV, Baxter CJ, Enfissi EM, Fraser PD. Carotenoid biosynthesis and sequestration in red chilli pepper fruit and its impact on colour intensity traits. J Exp Bot. 2019;70(10):2637–50.
Simkin AJ, Gaffé J, Alcaraz J-P, Carde J-P, Bramley PM, Fraser PD, et al. Fibrillin influence on plastid ultrastructure and pigment content in tomato fruit. Phytochemistry. 2007;68(11):1545–56.
Wang R, da Rocha Tavano EC, Lammers M, Martinelli AP, Angenent GC, de Maagd RA. Re-evaluation of transcription factor function in tomato fruit development and ripening with CRISPR/Cas9-mutagenesis. Sci Rep. 2019;9(1):1–10.
Li Z, Wu S, Chen J, Wang X, Gao J, Ren G, et al. NYEs/SGRs-mediated chlorophyll degradation is critical for detoxification during seed maturation in Arabidopsis. Plant J. 2017;92(4):650–61.
Zhu X, Chen J, Qiu K, Kuai B. Phytohormone and light regulation of chlorophyll degradation. Front Plant Sci. 2017;8:1911.
Xr Y, Xie X, Xj X, Yu J, Ferguson IB, Giovannoni JJ, et al. Involvement of an ethylene response factor in chlorophyll degradation during citrus fruit degreening. Plant J. 2016;86(5):403–12.
Lira BS, Gramegna G, Trench BA, Alves FRR, Silva EM, Silva GFF, et al. Manipulation of a senescence-associated gene improves fleshy fruit yield. Plant Physiol. 2017;175(1):77–91.
Henry RJ, Furtado A, Rangan P. Pathways of photosynthesis in non-leaf tissues. Biology. 2020;9(12):438.
Aschan G, Pfanz H. Non-foliar photosynthesis – a strategy of additional carbon acquisition. Flora. 2003;198(2):81–97.
Smillie RM, Hetherington SE, Davies WJ. Photosynthetic activity of the calyx, green shoulder, pericarp, and locular parenchyma of tomato fruit. J Exp Bot. 1999;50(334):707–18.
Blanke MM, Lenz F. Fruit photosynthesis. Plant Cell Environ. 1989;12(1):31–46.
Simkin AJ. Genetic engineering for global food security: photosynthesis and biofortification. Plants. 2019;8(12):586.
Lv J, Zhang M, Bai L, Han X, Ge Y, Wang W, et al. Effects of 1-methylcyclopropene (1-MCP) on the expression of genes involved in the chlorophyll degradation pathway of apple fruit during storage. Food Chem. 2020;308:125707.
Li D, Zhang X, Li L, Soleimani Aghdam M, Wei X, Liu J, et al. Elevated CO2 delayed the chlorophyll degradation and anthocyanin accumulation in postharvest strawberry fruit. Food Chem. 2019;285:163–70.
Tan X-L, Fan Z-q, Kuang J-f, Lu W-j, Reiter RJ, Lakshmanan P, et al. Melatonin delays leaf senescence of Chinese flowering cabbage by suppressing ABFs-mediated abscisic acid biosynthesis and chlorophyll degradation. J Pineal Res. 2019;67(1):e12570.
Wei F, Fu M, Li J, Yang X, Chen Q, Tian S. Chlorine dioxide delays the reddening of postharvest green peppers by affecting the chlorophyll degradation and carotenoid synthesis pathways. Postharvest Biol Technol. 2019;156:110939.
Charoenchongsuk N, Ikeda K, Itai A, Oikawa A, Murayama H. Comparison of the expression of chlorophyll-degradation-related genes during ripening between stay-green and yellow-pear cultivars. Sci Hortic. 2015;181:89–94.
Kilambi HV, Manda K, Rai A, Charakana C, Bagri J, Sharma R, et al. Green-fruited Solanum habrochaites lacks fruit-specific carotenogenesis due to metabolic and structural blocks. J Exp Bot. 2017;68(17):4803–19.
Roca M, Hornero-Méndez D, Gandul-Rojas B, Mínguez-Mosquera MI. Stay-green phenotype slows the carotenogenic process in Capsicum annuum (L.) fruits. J Agric Food Chem. 2006;54(23):8782–7.
Liu L, Shao Z, Zhang M, Wang Q. Regulation of carotenoid metabolism in tomato. Mol Plant. 2015;8(1):28–39.
Joyard J, Ferro M, Masselon C, Seigneurin-Berny D, Salvi D, Garin J, et al. Chloroplast proteomics and the compartmentation of plastidial isoprenoid biosynthetic pathways. Mol Plant. 2009;2(6):1154–80.
Barsan C, Zouine M, Maza E, Bian W, Egea I, Rossignol M, et al. Proteomic analysis of chloroplast-to-chromoplast transition in tomato reveals metabolic shifts coupled with disrupted thylakoid biogenesis machinery and elevated energy-production components. Plant Physiol. 2012;160(2):708–25.
van Wijk KJ, Kessler F. Plastoglobuli: plastid microcompartments with integrated functions in metabolism, plastid developmental transitions, and environmental adaptation. Annu Rev Plant Biol. 2017;68:253–89.
Kolotilin I, Koltai H, Tadmor Y, Bar-Or C, Reuveni M, Meir A, et al. Transcriptional profiling of high pigment-2dg tomato mutant links early fruit plastid biogenesis with its overproduction of phytonutrients. Plant Physiol. 2007;145(2):389–401.
Waters MT, Moylan EC, Langdale JA. GLK transcription factors regulate chloroplast development in a cell-autonomous manner. Plant J. 2008;56(3):432–44.
Pan Y, Bradley G, Pyke K, Ball G, Lu C, Fray R, et al. Network inference analysis identifies an APRR2-like gene linked to pigment accumulation in tomato and pepper fruits. Plant Physiol. 2013;161(3):1476–85.
Nadakuduti SS, Holdsworth WL, Klein CL, Barry CS. KNOX genes influence a gradient of fruit chloroplast development through regulation of GOLDEN 2-LIKE expression in tomato. Plant J. 2014;78(6):1022–33.
Sagar M, Chervin C, Mila I, Hao Y, Roustan J-P, Benichou M, et al. SlARF4, an auxin response factor involved in the control of sugar metabolism during tomato fruit development. Plant Physiol. 2013;161(3):1362–74.
Yuan Y, Xu X, Gong Z, Tang Y, Wu M, Yan F, et al. Auxin response factor 6A regulates photosynthesis, sugar accumulation, and fruit development in tomato. Hortic Res. 2019;6(1):1–16.
Yuan Y, Mei L, Wu M, Wei W, Shan W, Gong Z, et al. SlARF10, an auxin response factor, is involved in chlorophyll and sugar accumulation during tomato fruit development. J Exp Bot. 2018;69(22):5507–18.
Powell AL, Nguyen CV, Hill T, Cheng KL, Figueroa-Balderas R, Aktas H, et al. Uniform ripening encodes a Golden 2-like transcription factor regulating tomato fruit chloroplast development. Science. 2012;336(6089):1711–5.
Josse E-M, Simkin AJ, Gaffé J, Labouré A-M, Kuntz M, Carol P. A plastid terminal oxidase associated with carotenoid desaturation during chromoplast differentiation. Plant Physiol. 2000;123(4):1427–36.
Enfissi EMA, Nogueira M, Bramley PM, Fraser PD. The regulation of carotenoid formation in tomato fruit. Plant J. 2017;89(4):774–88.
Wen X, Heller A, Wang K, Han Q, Ni Y, Carle R, et al. Carotenogenesis and chromoplast development during ripening of yellow, orange and red colored Physalis fruit. Planta. 2020;251(5):95.
Llorente B, Torres-Montilla S, Morelli L, Florez-Sarasa I, Matus JT, Ezquerro M, et al. Synthetic conversion of leaf chloroplasts into carotenoid-rich plastids reveals mechanistic basis of natural chromoplast development. Proc Natl Acad Sci. 2020;117(35):21796–803.
Sun T, Li L. Toward the ‘golden’ era: the status in uncovering the regulatory control of carotenoid accumulation in plants. Plant Sci. 2020;290:110331.
Szymanski J, Levin Y, Savidor A, Breitel D, Chappell-Maor L, Heinig U, et al. Label-free deep shotgun proteomics reveals protein dynamics during tomato fruit tissues development. Plant J. 2017;90(2):396–417.
D’Andrea L, Simon-Moya M, Llorente B, Llamas E, Marro M, Loza-Alvarez P, et al. Interference with Clp protease impairs carotenoid accumulation during tomato fruit ripening. J Exp Bot. 2018;69(7):1557–68.
Ling Q, Sadali NM, Soufi Z, Zhou Y, Huang B, Zeng Y, et al. The chloroplast-associated protein degradation pathway controls chromoplast development and fruit ripening in tomato. Nat Plants. 2021;7(5):655–66.
Klee HJ, Giovannoni JJ. Genetics and control of tomato fruit ripening and quality attributes. Annu Rev Genet. 2011;45:41–59.
Li S, Zhu B, Pirrello J, Xu C, Zhang B, Bouzayen M, et al. Roles of RIN and ethylene in tomato fruit ripening and ripening-associated traits. New Phytol. 2020;226(2):460–75.
Galpaz N, Wang Q, Menda N, Zamir D, Hirschberg J. Abscisic acid deficiency in the tomato mutant high-pigment 3 leading to increased plastid number and higher fruit lycopene content. Plant J. 2008;53(5):717–30.
Kai W, Wang J, Liang B, Fu Y, Zheng Y, Zhang W, et al. PYL9 is involved in the regulation of ABA signaling during tomato fruit ripening. J Exp Bot. 2019;70(21):6305–19.
Sun Y, Ji K, Liang B, Du Y, Jiang L, Wang J, et al. Suppressing ABA uridine diphosphate glucosyltransferase (Sl UGT 75C1) alters fruit ripening and the stress response in tomato. Plant J. 2017;91(4):574–89.
Sun L, Yuan B, Zhang M, Wang L, Cui M, Wang Q, et al. Fruit-specific RNAi-mediated suppression of SlNCED1 increases both lycopene and β-carotene contents in tomato fruit. J Exp Bot. 2012;63(8):3097–108.
Carretero-Paulet L, Cairó A, Botella-Pavía P, Besumbes O, Campos N, Boronat A, et al. Enhanced flux through the methylerythritol 4-phosphate pathway in Arabidopsis plants overexpressing deoxyxylulose 5-phosphate reductoisomerase. Plant Mol Biol. 2006;62(4):683–95.
Fantini E, Falcone G, Frusciante S, Giliberto L, Giuliano G. Dissection of tomato lycopene biosynthesis through virus-induced gene silencing. Plant Physiol. 2013;163(2):986–98.
Li F, Vallabhaneni R, Wurtzel ET. PSY3, a new member of the phytoene synthase gene family conserved in the Poaceae and regulator of abiotic stress-induced root carotenogenesis. Plant Physiol. 2008;146(3):1333–45.
Yuan H, Zhang J, Nageswaran D, Li L. Carotenoid metabolism and regulation in horticultural crops. Hortic Res. 2015;2(1):1–11.
Jang S-J, Jeong H-B, Jung A, Kang M-Y, Kim S, Ha S-H, et al. Phytoene synthase 2 can compensate for the absence of PSY1 in the control of color in Capsicum fruit. J Exp Bot. 2020;71(12):3417–27.
Welsch R, Maass D, Voegel T, DellaPenna D, Beyer P. Transcription factor RAP2. 2 and its interacting partner SINAT2: stable elements in the carotenogenesis of Arabidopsis leaves. Plant Physiol. 2007;145(3):1073–85.
Cazzonelli CI, Cuttriss AJ, Cossetto SB, Pye W, Crisp P, Whelan J, et al. Regulation of carotenoid composition and shoot branching in Arabidopsis by a chromatin modifying histone methyltransferase, SDG8. Plant Cell. 2009;21(1):39–53.
Cazzonelli CI, Pogson BJ. Source to sink: regulation of carotenoid biosynthesis in plants. Trends Plant Sci. 2010;15(5):266–74.
Bianchetti R, De Luca B, de Haro LA, Rosado D, Demarco D, Conte M, et al. Phytochrome-dependent temperature perception modulates isoprenoid Metabolism1. Plant Physiol. 2020;183(3):869–82.
Bou-Torrent J, Toledo-Ortiz G, Ortiz-Alcaide M, Cifuentes-Esquivel N, Halliday KJ, Martinez-García JF, et al. Regulation of carotenoid biosynthesis by shade relies on specific subsets of antagonistic transcription factors and cofactors. Plant Physiol. 2015;169(3):1584–94.
Llorente B, D'Andrea L, Ruiz-Sola MA, Botterweg E, Pulido P, Andilla J, et al. Tomato fruit carotenoid biosynthesis is adjusted to actual ripening progression by a light-dependent mechanism. Plant J. 2016;85(1):107–19.
Sankari M, Hridya H, Sneha P, Doss CGP, Ramamoorthy S. Effect of UV radiation and its implications on carotenoid pathway in Bixa orellana L. J Photochem Photobiol B Biol. 2017;176:136–44.
Zheng X, Giuliano G, Al-Babili S. Carotenoid biofortification in crop plants: citius, altius, fortius. Biochim Biophys Acta Mol Cell Biol Lipids. 1865;2020(11):158664.
Li X, Wang Y, Chen S, Tian H, Fu D, Zhu B, et al. Lycopene Is Enriched in Tomato Fruit by CRISPR/Cas9-Mediated Multiplex Genome Editing. Front Plant Sci. 2018;9:559.
D’Ambrosio C, Giorio G, Marino I, Merendino A, Petrozza A, Salfi L, et al. Virtually complete conversion of lycopene into β-carotene in fruits of tomato plants transformed with the tomato lycopene β-cyclase (tlcy-b) cDNA. Plant Sci. 2004;166(1):207–14.
Karniel U, Koch A, Zamir D, Hirschberg J. Development of zeaxanthin-rich tomato fruit through genetic manipulations of carotenoid biosynthesis. Plant Biotechnol J. 2020;18(11):2292–303.
Watkins JL, Pogson BJ. Prospects for carotenoid biofortification targeting retention and catabolism. Trends Plant Sci. 2020;25(5):501–12.
Simkin AJ, Laizet Y, Kuntz M. Plastid lipid associated proteins of the plant fibrillin family: structure, localisation, functions and gene expression. In: Pandalai SG, editor. Recent Research Developments in Biochemistry, vol. 5. India: Research Signpost; 2004. p. 307–16.
Jeffery J, Holzenburg A, King S. Physical barriers to carotenoid bioaccessibility. Ultrastructure survey of chromoplast and cell wall morphology in nine carotenoid-containing fruits and vegetables. J Sci Food Agric. 2012;92(13):2594–602.
Bangalore D, McGlynn W, Scott D. Effects of fruit maturity on watermelon ultrastructure and intracellular lycopene distribution. J Food Sci. 2008;73(5):S222–8.
Harris WM, Spurr AR. Chromoplasts of tomato fruits. II. The red tomato. Am J Bot. 1969;56(4):380–9.
Frey-Wyssling A, Schwegler F. Ultrastructure of the chromoplasts in the carrot root. J Ultrastruct Res. 1965;13(5–6):543–59.
Paolillo D, Garvin D, Parthasarathy M. The chromoplasts of Or mutants of cauliflower (Brassica oleracea L. var. botrytis). Protoplasma. 2004;224(3–4):245–53.
Zacarías-García J, Lux PE, Carle R, Schweiggert RM, Steingass CB, Zacarías L, et al. Characterization of the pale yellow petal/xanthophyll esterase gene family in citrus as candidates for carotenoid esterification in fruits. Food Chem. 2021;342:128322.
Ariizumi T, Kishimoto S, Kakami R, Maoka T, Hirakawa H, Suzuki Y, et al. Identification of the carotenoid modifying gene PALE YELLOW PETAL 1 as an essential factor in xanthophyll esterification and yellow flower pigmentation in tomato (S olanum lycopersicum). Plant J. 2014;79(3):453–65.
Watkins JL, Li M, McQuinn RP, Chan KX, McFarlane HE, Ermakova M, et al. A GDSL esterase/lipase catalyzes the esterification of lutein in bread wheat. Plant Cell. 2019;31(12):3092–112.
Kim S, Ha TY, Hwang IK. Analysis, bioavailability, and potential healthy effects of capsanthin, natural red pigment from Capsicum spp. Food Rev Int. 2009;25(3):198–213.
Camara B, Moneger R. Carotenoid biosynthesis in vitro conversion of antheraxanthin to capsanthin by a chromoplast enriched fraction of Capsicum fruits. Biochem Biophys Res Commun. 1981;99(4):1117–22.
Hugueney P, Badillo A, Chen HC, Klein A, Hirschberg J, Camara B, et al. Metabolism of cyclic carotenoids: a model for the alteration of this biosynthetic pathway in Capsicum annuum chromoplasts. Plant J. 1995;8(3):417–24.
Kuntz M, Chen HC, Simkin AJ, Römer S, Shipton CA, Drake R, et al. Upregulation of two ripening-related genes from a non-climacteric plant (pepper) in a transgenic climacteric plant (tomato). Plant J. 1998;13(3):351–61.
Sun T, Xu Z, Wu CT, Janes M, Prinyawiwatkul W, No H. Antioxidant activities of different colored sweet bell peppers (Capsicum annuum L.). J Food Sci. 2007;72(2):S98–S102.
Maoka T, Akimoto N, Fujiwara Y, Hashimoto K. Structure of new carotenoids with the 6-Oxo-κ end group from the fruits of paprika, Capsicum a nnuum. J Nat Prod. 2004;67(1):115–7.
Ma L, Mu J, Grierson D, Wang Y, Gao L, Zhao X, et al. Noncoding RNAs: functional regulatory factors in tomato fruit ripening. Theor Appl Genet. 2020;133(5):1753–62.
Auldridge ME, Block A, Vogel JT, Dabney-Smith C, Mila I, Bouzayen M, et al. Characterization of three members of the Arabidopsis carotenoid cleavage dioxygenase family demonstrates the divergent roles of this multifunctional enzyme family. Plant J. 2006;45(6):982–93.
Gonzalez-Jorge S, Ha S-H, Magallanes-Lundback M, Gilliland LU, Zhou A, Lipka AE, et al. Carotenoid cleavage dioxygenase4 is a negative regulator of β-carotene content in Arabidopsis seeds. Plant Cell. 2013;113. https://doi.org/10.1105/tpc.113.119677.
Schwartz SH, Qin X, Loewen MC. The biochemical characterization of two carotenoid cleavage enzymes from Arabidopsis indicates that a carotenoid-derived compound inhibits lateral branching. J Biol Chem. 2004;279(45):46940–5.
Snowden KC, Simkin AJ, Janssen BJ, Templeton KR, Loucas HM, Simons JL, et al. The decreased apical dominance1/Petunia hybrida carotenoid cleavage dioxygenase8 gene affects branch production and plays a role in leaf senescence, root growth, and flower development. Plant Cell. 2005;17(3):746–59.
Vogel JT, Walter MH, Giavalisco P, Lytovchenko A, Kohlen W, Charnikhova T, et al. SlCCD7 controls strigolactone biosynthesis, shoot branching and mycorrhiza-induced apocarotenoid formation in tomato. Plant J. 2010;61(2):300–11.
Tan BC, Joseph LM, Deng WT, Liu L, Li QB, Cline K, et al. Molecular characterization of the Arabidopsis 9-cis epoxycarotenoid dioxygenase gene family. Plant J. 2003;35(1):44–56.
Meléndez-Martínez AJ. An overview of carotenoids, apocarotenoids, and vitamin a in agro-food, nutrition, health, and disease. Mol Nutr Food Res. 2019;63(15):1801045.
Sankari M, Rao PR, Hemachandran H, Pullela PK, Tayubi IA, Subramanian B, et al. Prospects and progress in the production of valuable carotenoids: insights from metabolic engineering, synthetic biology, and computational approaches. J Biotechnol. 2018;266:89–101.
Ramamoorthy S, Madrid RR, Doss CGP. Biology, Chemistry and Applications of Apocarotenoids: CRC Press; 2020.
Moshiri M, Vahabzadeh M, Hosseinzadeh H. Clinical applications of saffron (Crocus sativus) and its constituents: a review. Drug Res (Stuttg). 2015;65(6):287–95.
Pashirzad M, Shafiee M, Avan A, Ryzhikov M, Fiuji H, Bahreyni A, et al. Therapeutic potency of crocin in the treatment of inflammatory diseases: current status and perspective. J Cell Physiol. 2019;234(9):14601–11.
Goff SA, Klee HJ. Plant volatile compounds: sensory cues for health and nutritional value? Science. 2006;311(5762):815–9.
Simkin AJ, Schwartz SH, Auldridge M, Taylor MG, Klee HJ. The tomato carotenoid cleavage dioxygenase 1 genes contribute to the formation of the flavor volatiles β-ionone, pseudoionone, and geranylacetone. Plant J. 2004;40(6):882–92.
Simkin AJ, Underwood BA, Auldridge M, Loucas HM, Shibuya K, Schmelz E, et al. Circadian regulation of the PhCCD1 carotenoid cleavage dioxygenase controls emission of β-ionone, a fragrance volatile of petunia flowers. Plant Physiol. 2004;136(3):3504–14.
Giberti S, Giovannini D, Forlani G. Carotenoid cleavage in chromoplasts of white and yellow-fleshed peach varieties. J Sci Food Agric. 2019;99(4):1795–803.
Adami M, De Franceschi P, Brandi F, Liverani A, Giovannini D, Rosati C, et al. Identifying a carotenoid cleavage dioxygenase (ccd4) gene controlling yellow/white fruit flesh color of peach. Plant Mol Biol Report. 2013;31(5):1166–75.
Fukamatsu Y, Tamura T, Hihara S, Oda K. Mutations in the CCD4 carotenoid cleavage dioxygenase gene of yellow-flesh peaches. Biosci Biotechnol Biochem. 2013;77(12):2514–6.
Ma G, Zhang L, Matsuta A, Matsutani K, Yamawaki K, Yahata M, et al. Enzymatic formation of β-citraurin from β-cryptoxanthin and zeaxanthin by carotenoid cleavage dioxygenase4 in the flavedo of citrus fruit. Plant Physiol. 2013;163(2):682–95.
Rodrigo MJ, Alquézar B, Alós E, Medina V, Carmona L, Bruno M, et al. A novel carotenoid cleavage activity involved in the biosynthesis of Citrus fruit-specific apocarotenoid pigments. J Exp Bot. 2013;64(14):4461–78.
Li L, Yuan H. Chromoplast biogenesis and carotenoid accumulation. Arch Biochem Biophys. 2013;539(2):102–9.
Vishnevetsky M, Ovadis M, Itzhaki H, Levy M, Libal-Weksler Y, Adam Z, et al. Molecular cloning of a carotenoid-associated protein from Cucumis sativus corollas: homologous genes involved in carotenoid sequestration in chromoplasts. Plant J. 1996;10(6):1111–8.
Vishnevetsky M, Ovadis M, Vainstein A. Carotenoid sequestration in plants: the role of carotenoid-associated proteins. Trends Plant Sci. 1999;4(6):232–5.
Lopez AB, Van Eck J, Conlin BJ, Paolillo DJ, O'neill J, Li L. Effect of the cauliflower Or transgene on carotenoid accumulation and chromoplast formation in transgenic potato tubers. J Exp Bot. 2008;59(2):213–23.
Tzuri G, Zhou X, Chayut N, Yuan H, Portnoy V, Meir A, et al. A ‘golden’SNP in CmOr governs the fruit flesh color of melon (C ucumis Melo). Plant J. 2015;82(2):267–79.
Yazdani M, Sun Z, Yuan H, Zeng S, Thannhauser TW, Vrebalov J, et al. Ectopic expression of ORANGE promotes carotenoid accumulation and fruit development in tomato. Plant Biotechnol J. 2019;17(1):33–49.
Osorio CE. The role of Orange gene in carotenoid accumulation: manipulating Chromoplasts toward a colored future. Front Plant Sci. 2019;10:1235.
D’Andrea L, Rodriguez-Concepcion M. Manipulation of plastidial protein quality control components as a new strategy to improve carotenoid contents in tomato fruit. Front Plant Sci. 2019;10:1071.
Berman J, Zorrilla-López U, Medina V, Farré G, Sandmann G, Capell T, et al. The Arabidopsis ORANGE (AtOR) gene promotes carotenoid accumulation in transgenic corn hybrids derived from parental lines with limited carotenoid pools. Plant Cell Rep. 2017;36(6):933–45.
Beyene G, Solomon FR, Chauhan RD, Gaitan-Solis E, Narayanan N, Gehan J, et al. Provitamin a biofortification of cassava enhances shelf life but reduces dry matter content of storage roots due to altered carbon partitioning into starch. Plant Biotechnol J. 2017;16(6):1186–200.
Andersen TB, Llorente B, Morelli L, Torres-Montilla S, Bordanaba-Florit G, Espinosa FA, et al. An engineered extraplastidial pathway for carotenoid biofortification of leaves. Plant Biotechnol J. 2021;19(5):1008.
Majer E, Llorente B, Rodríguez-Concepción M, Daròs J-A. Rewiring carotenoid biosynthesis in plants using a viral vector. Sci Rep. 2017;7(1):1–10.
Torres-Montilla S, Rodriguez-Concepcion M. Making extra room for carotenoids in plant cells: new opportunities for biofortification. Prog Lipid Res. 2021;84:101128.
Mazza G. Anthocyanins in fruits, vegetables, and grains: CRC press; 2018.
Patel PR, Rao TR. Growth and ripening in black plum [Syzygium cumini (L.) Skeels]. Int J fruit Sci. 2014;14(2):147–56.
Zhao X, Yuan Z, Yin Y, Feng L. Patterns of pigment changes in pomegranate (Punica granatum L.) peel during fruit ripening. Acta Hortic. 2015;1089:83–9.
Cox KA, McGhie TK, White A, Woolf AB. Skin colour and pigment changes during ripening of ‘Hass’ avocado fruit. Postharvest Biol Technol. 2004;31(3):287–94.
Gonçalves B, Silva AP, Moutinho-Pereira J, Bacelar E, Rosa E, Meyer AS. Effect of ripeness and postharvest storage on the evolution of colour and anthocyanins in cherries (Prunus avium L.). Food Chem. 2007;103(3):976–84.
Starkevič P, Ražanskienė A, Starkevič U, Kazanavičiūtė V, Denkovskienė E, Bendokas V, et al. Isolation and analysis of anthocyanin pathway genes from Ribes genus reveals MYB gene with potent anthocyanin-inducing capabilities. Plants. 2020;9(9):1078.
Tan L, Ijaz U, Salih H, Cheng Z, Ni Win Htet N, Ge Y, et al. Genome-wide identification and comparative analysis of MYB transcription factor family in Musa acuminata and Musa balbisiana. Plants. 2020;9(4):413.
Solfanelli C, Poggi A, Loreti E, Alpi A, Perata P. Sucrose-specific induction of the anthocyanin biosynthetic pathway in Arabidopsis. Plant Physiol. 2006;140(2):637–46.
Loreti E, Povero G, Novi G, Solfanelli C, Alpi A, Perata P. Gibberellins, jasmonate and abscisic acid modulate the sucrose-induced expression of anthocyanin biosynthetic genes in Arabidopsis. New Phytol. 2008;179(4):1004–16.
An J-P, Wang X-F, Li Y-Y, Song L-Q, Zhao L-L, You C-X, et al. EIN3-LIKE1, MYB1, and ethylene response factor3 act in a regulatory loop that synergistically modulates ethylene biosynthesis and anthocyanin accumulation. Plant Physiol. 2018;178(2):808–23.
Zhang J, Xu H, Wang N, Jiang S, Fang H, Zhang Z, et al. The ethylene response factor MdERF1B regulates anthocyanin and proanthocyanidin biosynthesis in apple. Plant Mol Biol. 2018;98(3):205–18.
Kwon Y, Oh JE, Noh H, Hong SW, Bhoo SH, Lee H. The ethylene signaling pathway has a negative impact on sucrose-induced anthocyanin accumulation in Arabidopsis. J Plant Res. 2011;124(1):193–200.
Ji X-H, Wang Y-T, Zhang R, Wu S-J, An M-M, Li M, et al. Effect of auxin, cytokinin and nitrogen on anthocyanin biosynthesis in callus cultures of red-fleshed apple (Malus sieversii f. niedzwetzkyana). Plant Cell Tiss Organ Cult (PCTOC). 2015;120(1):325–37.
Wang Y-c, Wang N, Xu H-f, Jiang S-h, Fang H-c, Su M-y, et al. Auxin regulates anthocyanin biosynthesis through the aux/IAA–ARF signaling pathway in apple. Hortic Res. 2018;5(1):1–11.
Chung SW, Yu DJ, Oh HD, Ahn JH, Huh JH, Lee HJ. Transcriptional regulation of abscisic acid biosynthesis and signal transduction, and anthocyanin biosynthesis in ‘Bluecrop’highbush blueberry fruit during ripening. Plos One. 2019;14(7):e0220015.
Li G, Zhao J, Qin B, Yin Y, An W, Mu Z, et al. ABA mediates development-dependent anthocyanin biosynthesis and fruit coloration in Lycium plants. BMC Plant Biol. 2019;19(1):1–13.
Karppinen K, Tegelberg P, Häggman H, Jaakola L. Abscisic acid regulates anthocyanin biosynthesis and gene expression associated with cell wall modification in ripening bilberry (Vaccinium myrtillus L.) fruits. Front Plant Sci. 2018;9:1259.
Davuluri GR, Van Tuinen A, Fraser PD, Manfredonia A, Newman R, Burgess D, et al. Fruit-specific RNAi-mediated suppression of DET1 enhances carotenoid and flavonoid content in tomatoes. Nat Biotechnol. 2005;23(7):890–5.
Muir SR, Collins GJ, Robinson S, Hughes S, Bovy A, De Vos CR, et al. Overexpression of petunia chalcone isomerase in tomato results in fruit containing increased levels of flavonols. Nat Biotechnol. 2001;19(5):470–4.
Butelli E, Titta L, Giorgio M, Mock H-P, Matros A, Peterek S, et al. Enrichment of tomato fruit with health-promoting anthocyanins by expression of select transcription factors. Nat Biotechnol. 2008;26(11):1301–8.
Zhang Y, Butelli E, Alseekh S, Tohge T, Rallapalli G, Luo J, et al. Multi-level engineering facilitates the production of phenylpropanoid compounds in tomato. Nat Commun. 2015;6(1):1–11.
Hassanin AA, Saad AM, Bardisi EA, Salama A, Sitohy MZ. Transfer of anthocyanin accumulating delila and rosea1 genes from the transgenic tomato micro-tom cultivar to moneymaker cultivar by conventional breeding. J Agric Food Chem. 2020;68(39):10741–9.
Jian W, Cao H, Yuan S, Liu Y, Lu J, Lu W, et al. SlMYB75, an MYB-type transcription factor, promotes anthocyanin accumulation and enhances volatile aroma production in tomato fruits. Hortic Res. 2019;6(1):1–15.
Riaz M, Zia-Ul-Haq M, Saad B: Biosynthesis and stability of anthocyanins. In: Anthocyanins and Human Health: Biomolecular and therapeutic aspects. Springer; 2016: 71–86. https://doi.org/10.1007/978-3-319-26456-1_6.
Zhou L-L, Shi M-Z, Xie D-Y. Regulation of anthocyanin biosynthesis by nitrogen in TTG1–GL3/TT8–PAP1-programmed red cells of Arabidopsis thaliana. Planta. 2012;236(3):825–37.
Azuma A, Yakushiji H, Koshita Y, Kobayashi S. Flavonoid biosynthesis-related genes in grape skin are differentially regulated by temperature and light conditions. Planta. 2012;236(4):1067–80.
Lai B, Li X-J, Hu B, Qin Y-H, Huang X-M, Wang H-C, et al. LcMYB1 is a key determinant of differential anthocyanin accumulation among genotypes, tissues, developmental phases and ABA and light stimuli in Litchi chinensis. Plos One. 2014;9(1):e86293.
Li Y-Y, Mao K, Zhao C, Zhao X-Y, Zhang H-L, Shu H-R, et al. MdCOP1 ubiquitin E3 ligases interact with MdMYB1 to regulate light-induced anthocyanin biosynthesis and red fruit coloration in apple. Plant Physiol. 2012. https://doi.org/10.1104/pp.112.199703.
Lau OS, Deng XW. The photomorphogenic repressors COP1 and DET1: 20 years later. Trends Plant Sci. 2012;17(10):584–93.
Peng T, Saito T, Honda C, Ban Y, Kondo S, Liu JH, et al. Screening of UV-B-induced genes from apple peels by SSH: possible involvement of MdCOP1-mediated signaling cascade genes in anthocyanin accumulation. Physiol Plant. 2013;148(3):432–44.
Zhang Z-Z, Li X-X, Chu Y-N, Zhang M-X, Wen Y-Q, Duan C-Q, et al. Three types of ultraviolet irradiation differentially promote expression of shikimate pathway genes and production of anthocyanins in grape berries. Plant Physiol Biochem. 2012;57:74–83.
Zhang Z-Z, Che X-N, Pan Q-H, Li X-X, Duan C-Q. Transcriptional activation of flavan-3-ols biosynthesis in grape berries by UV irradiation depending on developmental stage. Plant Sci. 2013;208:64–74.
Liu M, Li X, Liu Y, Cao B. Regulation of flavanone 3-hydroxylase gene involved in the flavonoid biosynthesis pathway in response to UV-B radiation and drought stress in the desert plant, Reaumuria soongorica. Plant Physiol Biochem. 2013;73:161–7.
Luo H, Dai C, Li Y, Feng J, Liu Z, Kang C. Reduced anthocyanins in petioles codes for a GST anthocyanin transporter that is essential for the foliage and fruit coloration in strawberry. J Exp Bot. 2018;69(10):2595–608.
Mazza G, Francis F. Anthocyanins in grapes and grape products. Crit Rev Food Sci Nutr. 1995;35(4):341–71.
Jackson RS. Wine science: principles and applications: Academic press; 2008.
Janvary L, Hoffmann T, Pfeiffer J, Hausmann L, Töpfer R, Fischer TC, et al. A double mutation in the anthocyanin 5-O-glucosyltransferase gene disrupts enzymatic activity in Vitis vinifera L. J Agric Food Chem. 2009;57(9):3512–8.
Hugueney P, Provenzano S, Verriès C, Ferrandino A, Meudec E, Batelli G, et al. A novel cation-dependent O-methyltransferase involved in anthocyanin methylation in grapevine. Plant Physiol. 2009;150(4):2057–70.
García-Beneytez E, Cabello F, Revilla E. Analysis of grape and wine anthocyanins by HPLC-MS. J Agric Food Chem. 2003;51(19):5622–9.
Morata A, Calderón F, González M, Gómez-Cordovés M, Suárez J. Formation of the highly stable pyranoanthocyanins (vitisins a and B) in red wines by the addition of pyruvic acid and acetaldehyde. Food Chem. 2007;100(3):1144–52.
Markham KR, Gould KS, Winefield CS, Mitchell KA, Bloor SJ, Boase MR. Anthocyanic vacuolar inclusions—their nature and significance in flower colouration. Phytochemistry. 2000;55(4):327–36.
Kallam K, Appelhagen I, Luo J, Albert N, Zhang H, Deroles S, et al. Aromatic decoration determines the formation of anthocyanic vacuolar inclusions. Curr Biol. 2017;27(7):945–57.
Francisco RM, Regalado A, Ageorges A, Burla BJ, Bassin B, Eisenach C, et al. ABCC1, an ATP binding cassette protein from grape berry, transports anthocyanidin 3-O-glucosides. Plant Cell. 2013. https://doi.org/10.1105/tpc.112.102152.
Zhao J, Huhman D, Shadle G, He X-Z, Sumner LW, Tang Y, et al. MATE2 mediates vacuolar sequestration of flavonoid glycosides and glycoside malonates in Medicago truncatula. Plant Cell. 2011. https://doi.org/10.1105/tpc.110.080804.
Kitamura S, Shikazono N, Tanaka A. Transparent testa 19 is involved in the accumulation of both anthocyanins and proanthocyanidins in Arabidopsis. Plant J. 2004;37(1):104–14.
Sun Y, Li H, Huang J-R. Arabidopsis TT19 functions as a carrier to transport anthocyanin from the cytosol to tonoplasts. Mol Plant. 2012;5(2):387–400.
Hu B, Zhao J, Lai B, Qin Y, Wang H, Hu G. LcGST4 is an anthocyanin-related glutathione S-transferase gene in Litchi chinensis Sonn. Plant Cell Rep. 2016;35(4):831–43.
Cheng J, Liao L, Zhou H, Gu C, Wang L, Han Y. A small indel mutation in an anthocyanin transporter causes variegated colouration of peach flowers. J Exp Bot. 2015;66(22):7227–39.
El-Sharkawy I, Liang D, Xu K. Transcriptome analysis of an apple (Malus× domestica) yellow fruit somatic mutation identifies a gene network module highly associated with anthocyanin and epigenetic regulation. J Exp Bot. 2015;66(22):7359–76.
Chung C, Rojanasasithara T, Mutilangi W, McClements DJ. Stabilization of natural colors and nutraceuticals: inhibition of anthocyanin degradation in model beverages using polyphenols. Food Chem. 2016;212:596–603.
Trouillas P, Sancho-García JC, De Freitas V, Gierschner J, Otyepka M, Dangles O. Stabilizing and modulating color by copigmentation: insights from theory and experiment. Chem Rev. 2016;116(9):4937–82.
Polturak G, Heinig U, Grossman N, Battat M, Leshkowitz D, Malitsky S, et al. Transcriptome and metabolic profiling provides insights into betalain biosynthesis and evolution in Mirabilis Jalapa. Mol Plant. 2018;11(1):189–204.
Ansari M, Emami S. β-ionone and its analogs as promising anticancer agents. Eur J Med Chem. 2016;123:141–54.
Milani A, Basirnejad M, Shahbazi S, Bolhassani A. Carotenoids: biochemistry, pharmacology and treatment. Br J Pharmacol. 2017;174(11):1290–324.
Niranjana R, Gayathri R, Nimish Mol S, Sugawara T, Hirata T, Miyashita K, et al. Carotenoids modulate the hallmarks of cancer cells. J Funct Foods. 2015;18:968–85.
Rodríguez-Pulido FJ, Gil-Vicente M, Gordillo B, Heredia FJ, González-Miret ML. Measurement of ripening of raspberries (Rubus idaeus L) by near infrared and colorimetric imaging techniques. J Food Sci Technol. 2017;54(9):2797–803.
van Roy J, Keresztes J, Wouters N, De Ketelaere B, Saeys W. Measuring colour of vine tomatoes using hyperspectral imaging. Postharvest Biol Technol. 2017;129:79–89.
Vanoli M, Buccheri M. Overview of the methods for assessing harvest maturity; 2012.
Taghadomi-Saberi S, Omid M, Emam-Djomeh Z, Faraji-Mahyari K. Determination of cherry color parameters during ripening by artificial neural network assisted image processing technique. J Agric Sci Technol. 2015;17(3):589–600.
Li X, Jin J, Sun C, Ye D, Liu Y. Simultaneous determination of six main types of lipid-soluble pigments in green tea by visible and near-infrared spectroscopy. Food Chem. 2019;270:236–42.
Agati G, D’Onofrio C, Ducci E, Cuzzola A, Remorini D, Tuccio L, et al. Potential of a multiparametric optical sensor for determining in situ the maturity components of red and white Vitis vinifera wine grapes. J Agric Food Chem. 2013;61(50):12211–8.
Li B, Lecourt J, Bishop G. Advances in non-destructive early assessment of fruit ripeness towards defining optimal time of harvest and yield prediction—a review. Plants. 2018;7(1):3.
Martín-Pizarro C, Posé D. Genome editing as a tool for fruit ripening manipulation. Front Plant Sci. 2018;9:1415.
Zsögön A, Čermák T, Naves ER, Notini MM, Edel KH, Weinl S, et al. De novo domestication of wild tomato using genome editing. Nat Biotechnol. 2018;36(12):1211–6.
Noorbala AA, Akhondzadeh S, Tahmacebi-Pour N, Jamshidi AH. Hydro-alcoholic extract of Crocus sativus L. versus fluoxetine in the treatment of mild to moderate depression: a double-blind, randomized pilot trial. J Ethnopharmacol. 2005;97(2):281–4.
Raines CA, Cavanagh AP, Simkin AJ. Chapter 9. Improving carbon fixation. In: Ruban A, Murchie E, Foyer C, editors. Photosynthesis in Action. 1st ed: Academic Press; 2022.
Simkin AJ, Lopez-Calcagno PE, Raines CA. Feeding the world: improving photosynthetic efficiency for sustainable crop production. J Exp Bot. 2019;70(4):1119–40.
The authors are thankful to VIT Management for their support and encouragement.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. A.J.S is supported by the Growing Kent and Medway Program, UK; Ref 107139.
Consent to publication
Ethics approval and consent to participate
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Kapoor, L., Simkin, A.J., George Priya Doss, C. et al. Fruit ripening: dynamics and integrated analysis of carotenoids and anthocyanins. BMC Plant Biol 22, 27 (2022). https://doi.org/10.1186/s12870-021-03411-w
- Fruit ripening, chlorophyll
- Pigment dynamics