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Hordeum chilense genome, a useful tool to investigate the endosperm yellow pigment content in the Triticeae



The wild barley Hordeum chilense fulfills some requirements for being a useful tool to investigate the endosperm yellow pigment content (YPC) in the Triticeae including its diploid constitution, the availability of genetic resources (addition and deletion stocks and a high density genetic map) and, especially, its high seed YPC not silenced in tritordeums (amphiploids derived from H. chilense and wheat). Thus, the aim of this work was to test the utility of the H. chilense genome for investigating the YPC in the Triticeae.


Twelve genes related to endosperm carotenoid content and/or YPC in grasses (Dxr, Hdr [synonym ispH], Ggpps1, Psy2, Psy3, Pds, Zds, e-Lcy, b-Lcy, Hyd3, Ccd1 and Ppo1) were identified, and mapped in H. chilense using rice genes to identify orthologs from barley, wheat, sorghum and maize. Macrocolinearity studies revealed that gene positions were in agreement in H. vulgare and H. chilense. Additionally, three main regions associated with YPC were identified in chromosomes 2Hch, 3Hch and 7Hch in H. chilense, the former being the most significant one.


The results obtained are consistent with previous findings in wheat and suggest that Ggpps1, Zds and Hyd3 on chromosome 2Hch may be considered candidate genes in wheat for further studies in YPC improvement. Considering the syntenic location of carotenoid genes in H. chilense, we have concluded that the Hch genome may constitute a valuable tool for YPC studies in the Triticeae.


Hordeum chilense Roem. et Schultz. is a diploid wild barley included in the section Anisolepis Nevski, native to Chile and Argentina. This species has been used as a new source of cytoplasmic male sterility for hybrid wheat production [13] and it shows other potentially useful traits for wheat breeding, including immunity to Septoria tritici blotch and high seed yellow pigment content (YPC) [46]. The compatibility of the H. chilense genome with Triticum spp. is high, and fertile amphiploids, named tritordeums (×Tritordeum Ascherson et Graebner), have been developed from the hybrid between H. chilense and durum or common wheat [7, 8]. Tritordeums are subjected to a breeding program at IAS-CSIC conducted by Prof. A. Martín with the goal of obtaining a new crop. Additionally, they are also useful as a genetic bridge to transfer H. chilense genes to both common and durum wheat [9].

One of the most valuable traits of this new cereal is the high endosperm YPC given by H. chilense genes. The YPC, mainly caused by carotenoids, is also very important in durum wheat due to its relation to semolina quality [1013]. In addition, the consumption of carotenoid-rich foods has been associated with a reduced risk of developing certain types of diseases [14, 15]. Besides, carotenoids with unsubstituted β-ionone rings, such as β-carotene, have provitamin A activity [16] while other carotenoids such as lutein may prevent age-related macular degradation [17, 18]. Accordingly, seed carotenoid content is receiving more attention with the goal of developing new functional foods.

The carotenoid biosynthesis pathway is well known in plants [16, 1922]. Candidate gene studies in maize have shown the role of several carotenoid-related genes in endosperm carotenoid content using quantitative trait locus (QTL) and association studies. Indeed, several genes including Psy1[2325]; Zds[25]; e Lcy[26]; Ziso[27] and Hyd3[28] have been related to endosperm carotenoid content. Genes from both upstream and downstream pathways have also been investigated at the transcriptomic level in maize [29].

Despite the importance of YPC in durum wheat and tritordeums and the positive correlation between YPC and carotenoid content, candidate gene studies for YPC in both species are mostly based on Phytoene synthase 1 gene (Psy1). PSY1 catalyzes the first step of the carotenoid biosynthetic pathway and it is considered a limiting factor for carotenoid production [18, 30]. Since the first reports about the location of Psy1 to chromosomes 7A and 7B in wheat [31, 32], a considerable amount of work has demonstrated the role of this gene in durum wheat YPC [3339]. In addition, the lycopene epsilon cyclase gene (e Lcy) has been co-localized with a QTL for YPC in wheat [35]. Nevertheless the role of other candidate genes for YPC in durum wheat remains largely unexplored. Given the high level of macrocolinearity among grasses, the knowledge gained in any species may be useful in others. This is more evident within the Triticeae due to the close relationship among these species. Indeed, Triticeae species are represented as a single genome in comparative studies [40, 41].

In this context H. chilense may be a useful species to investigate the role of carotenoid-related genes in the YPC in the Triticeae. First, it exhibits a high YPC which is not silenced in wheat background, as evidenced in tritordeums [10, 42, 43]. Second, the diploid constitution of this species and the existence of H. chilense-wheat chromosome addition lines [44] and other deletion stocks [45, 46] makes the identification of candidate genes more accessible. Third, a high density genetic map has been recently developed using H. chilense-derived DArT markers [47] which allows efficient candidate gene mapping and comparative studies.

The objective of this work is to determine whether H. chilense could be useful for investigating the endosperm YPC in the Triticeae. For this purpose we aimed to identify and locate a set of carotenoid-related genes previously studied in other grasses and to determine the macrocolinearity between H. chilense and barley for these genes. In the second place, we aimed to identify the main regions for YPC in H. chilense and to discuss the results obtained in relation to wheat.


Plant material

Hordeum chilense accession lines H1 and H7 from the collection of the Instituto de Agricultura Sostenible (IAS-CSIC, Córdoba) were used for polymorphism detection in the selected genes. DNA of 92 F7-Recombinant Inbred Lines (RILs) derived from the cross H1 × H7 was used for genetic mapping of the gene-based markers designed. These lines were sown in small pods with five seeds each. After initial growing, RILs were transplanted to field conditions using a randomized plot design with two replications.

For physical mapping, the following common wheat cv. Chinese Spring (CS)-H. chilense addition lines were used: with complete chromosomes 1Hch, 4Hch, 5Hch, 6Hch or 7Hch (named CS MA 1Hch-1 HchS, CS DA4Hch, CS DA5Hch, CS DA6Hch and CS DA7Hch, respectively, where MA refers to monosomic addition and DA to disomic addition), and (CS)-H. chilense ditelosomic addition lines CS DA1HchS, CS DA2HchS, CS DA5HchL, CS DA6HchS, CS DA7Hchα, CS DA7Hchβ.

Leaf tissue was harvested at tillering stage, frozen in liquid nitrogen, and stored at -80°C. Genomic DNA was extracted using the CTAB method according to [48].

Primer design

The twelve genes were selected from the main steps of the carotenoid biosynthetic pathway but also from upstream and downstream pathways, considering previous results obtained in other grasses, mainly maize. Rice genes were used as a query to identify orthologous genes in maize, sorghum, wheat and/or barley (see Additional file 1). Nucleotide sequences were aligned to design primers in the conserved regions of each gene. Psy1 sequence of H. chilense was available from previous works [31, 49]. Sequences were aligned using Edialign program ( and edited using GeneDoc software ( Sequence identity searches were performed at the NCBI ( using BLAST. Primer pairs were designed using Primer3plus software [50] on exonic regions flanking at least one intron when possible.

PCR amplification and polymorphism detection

PCR amplifications were performed in 25 μl reactions consisting of 0.625 units of DNA polymerase (Biotools B&M Labs, Madrid, Spain), 1× PCR buffer, 1.6 mM MgCl2, 320 mM dNTPs (Promega, Madison, WI, USA), 0.6 mM of each primer and 50 ng of genomic DNA. PCR were carried out as follows: 5 min at 94°C, 35 cycles of 30 s at 94°C, 30 s at 58°C (54°C for Zds) and 1 min at 72°C followed by 7 min at 72°C. For allele-specific amplifications with tetra-primer PCR, the number of cycles was increased to 40 and the annealing temperature was set at 60°C. Amplification and digestion of Psy1 gene were carried out as described by [31]. PCR products were resolved on 2% agarose gels, stained with ethidium bromide and visualized under UV light. All primers used in this work are summarized in Table 1.

Table 1 Primers designed for amplification and mapping of the candidate genes

Nucleotide sequences were obtained by direct sequencing or by cloning if more than one product was observed in the amplifications. For cloning, pGEMT-Easy vector (Promega, Madison, WI) was used to transform competent Escherichia coli (DH5α) cells. Plasmids were isolated and purified using Illustra plasmid Prep Mini Spin Kit (GE Healthcare, UK Ltd, UK).

Digestion reactions with restriction enzymes HhaI, HinfI, MboII, NheI and TasI (Takara Bio Inc., Japan) were carried out following manufacturer’s instructions using 10 μl of PCR in a final volume of 20 μl.

Identification of genomic regions for endosperm yellow pigment content (YPC)

YPC was determined according to the AACC method 14–50 [51] in 71 F7-RILs, which yielded a sufficient amount of seed. Briefly, approximately 150 mg of flour was used to evaluate YPC. Pigment extraction was performed using water-saturated n-butanol in a 1:10 (w/v) ratio. Samples were centrifuged at 14,000 g for 10 min and the pigment was measured by absorbance reading at 435.8 nm. All determinations were performed in duplicate.

A DArT-based H. chilense map [47] constituted the basis for mapping. A framework map composed by markers spaced 3–5 cM was considered to determine trait-marker associations and QTL mapping since the use of very proximal markers results in highly similar LOD scores while it signifies a huge increase in the number of calculations. Gene-based markers were integrated in the H. chilense map using JoinMap 4.0 mapping software [52]. After linkage analysis, the position of each candidate gene within a chromosome was determined using the fixed order option, the Monte Carlo Maximum Likelihood Mapping algorithm (ML-mapping) module and the Kosambi mapping function.

Associations between markers and YPC were determined using the Kruskal-Wallis (KW) test and MapQTL 4.0 [53]. Regions showing at least five markers associated with YPC at p<0.01 were considered as YPC regions but further analyses were performed to identify the most significant ones. Marker cofactors were automatically selected using the automatic cofactor selection (ACS) tool at p<0.05. For both Interval Mapping (IM) and Multiple QTL Mapping (MQM), the genome-wide significance threshold was estimated using the permutation test with the following parameters: the walk speed was set to 3 cM; the number of permutations was set to 500 and the significance level to 0.05. The QTL position was estimated at the peak LOD with a 2-LOD support interval [54]. The map figure included in the manuscript was produced using MapChart software [55].


Gene-based marker design, amplification and mapping

A total of twelve genes not previously mapped in H. chilense were selected for this work: 1-deoxy-D-xylulose 5-phosphate reductoisomerase (Dxr) and 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (Hdr [synonym ispH]) from the MEP pathway; geranyl geranyl pyrophosphate synthase (Ggpps1) for geranylgeranyl diphosphate synthesis; phytoene synthase 2 (Psy2), phytoene synthase 3 (Psy3), phytoene dehydrogenase (Pds), zeta-carotene desaturase (Zds), lycopene epsilon cyclase (e-Lcy), lycopene beta cyclase (b-Lcy) and beta-carotene hydroxylase 3 (Hyd3) from the carotenoid biosynthetic pathway; the carotenoid cleavage dioxygenase 1 gene (Ccd1) mediating the degradation of carotenoids to apocarotenoids and polyphenol oxidase 1 gene (Ppo1) implicated in plant tissue enzymatic browning.

Rice genes ( were used as a query to identify orthologs from barley, wheat, sorghum and maize. Exon-intron boundaries and highly conserved regions were recognized by the alignment of each sequence set. Primers were designed on conserved exonic regions to amplify at least one intron and maximize polymorphism detection. Amplifications with the primers designed (Table 1) were carried out using the parental lines H1 and H7 as template. PCR products were sequenced to confirm their identity and examined for polymorphisms by comparing both parental lines.

All the candidate genes were successfully amplified and sequenced in H. chilense [GenBank: JQ922078-JQ922105]. Differences between H1 and H7 sequences were found for all the candidate genes, these being in most cases Single Nucleotide Polymorphisms (SNP) (Table 2). These SNPs were used to develop either Cleaved Amplified Polymorphism (CAP) markers for Zds, Hyd3, Pds, Hdr, Psy3 and e-Lcy or to design allele-specific primers. Specific amplifications were obtained by using tetra-primer PCR (to amplify both H1 and H7 alleles) for Ggpps1 (GGPPS1-F1/ GGPPS1-R1/ GGPPS1-spF/ GGPPS1-spR) and b-Lcy (LBC-F2/ LBC-R2/ LBC-spF/ LBC-spR). Alternatively, specific reverse primers CCD-spR and PSY2-spR were designed to use in combination with CCD-F1 and PSY2-F, respectively, to obtain PCR amplification exclusively in one of the parental alleles. Finally, length polymorphisms were detected for Dxr (14 bp insertion in H7 sequence compared to H1) and Ppo1. Regarding Ppo1, two sequences were amplified in H1 with primer pair PPO1-F1/PPO1-R1 differing in two SNPs (JQ922103 and JQ922104), both of them having in common a deletion of 23 bp compared to H7 (JQ922105). This was the length polymorphism scored in the mapping population.

Table 2 Polymorphism between H1 and H7 lines used for mapping

All gene-based markers were located in the H. chilense map (Figure 1) in the following chromosomes: 2Hch (Ggpps1, Zds, Hyd3 and Ppo1); 3Hch (Dxr and e Lcy); 4Hch (Hdr and Pds); 5Hch (Ccd1, Psy2 and Psy3); 6Hch (b Lcy). The position (cM) of each candidate gene in the map is shown in Table 3. Both Ggpps1 and Zds were tightly linked and mapped near the centromere which was estimated in a 11 cM window [47] while Hyd3 and Ppo1 were mapped to the long arm of chromosome 2Hch at 142.38 cM and 161.56 cM respectively. The e Lcy gene was located in the vicinity of the chromosome 3Hch centromere while Dxr was mapped to the distal part of the 3HchS arm (Figure 1). Hdr and Pds genes were mapped to 4HchS and 4HchL arms respectively. Ccd1 (distal) and Psy2 (39.06 cM) were mapped to chromosome 5HchS while Psy3 was mapped to the long arm of this chromosome (133.75 cM). Finally, b Lcy was mapped to the long arm of chromosome 6Hch (111.2 cM) since the centromere is estimated at 84.0 cM [47]. Also, Psy1 is located on chromosome arm 7Hchα as shown in previous studies using physical mapping [31, 47].

Figure 1
figure 1

Marker YPC association in the Kruskal Wallis (KW) analysis. To determine marker-YPC associations, a framework map composed by markers spaced around 3–5 cM was considered from the map developed by [47]. The estimated centromere position is shown as a coloured segment within each chromosome. In chromosomes 6Hch and 7Hch centromeres were located in a single position since markers belonging to different chromosome arms mapped at the same position. For chromosomes 6Hch and 7Hch, the estimated centromere locations are shown as black triangles. The position of the candidate genes mapped in this work is highlighted using a coloured box. The significance of the KW analysis is shown: - Not significant; *0.1; **0.05; ***0.01; ****0.005; *****0.001; ******0.0005; *******0.0001. Three locations with at least five markers associated with YPC were considered as YPC regions (Regions 1 to 3). The most significant zone within these regions was determined using MQM analysis and permutation test (identified as YPC at 2HchL) and its position estimated at the peak LOD with a 2-LOD support interval.

Table 3 Macrocolinearity between H. chilense and H. vulgare for the candidate genes selected

Physical mapping by using the series of addition lines of H. chilense in common wheat was also possible for genes Hdr, Ggpps1, Psy2, Zds and Ccd1. Physical location could not be confirmed for genes located on chromosomes 2HchL and 3Hch (since there are no addition lines for these chromosomes) or when polymorphism with wheat was not detected with the designed markers (b-Lcy, Psy3, Pds and Ppo1).

To study the macrocolinearity between H. chilense and barley for these candidate genes, the Poaceae orthologous group corresponding to each candidate gene was identified from using the rice gene as query (Table 3). Orthologous genes in Brachypodium and Sorghum were identified by this means. The RAP locus identifier was retrieved using the ID Converter tool ( Rice, barley and sorghum orthologs were located in the Barley Genome Zipper [56], which allowed the determination of their relative positions in the barley map [57] in all cases except for Zds which was not found in the Barley Genome Zipper (Table 3). The Psy1, previously mapped in H. chilense, was also located in barley.

Determination of YPC regions in H. chilense

The YPC content was determined in the H1×H7 RIL mapping population. Kruskall-Wallis (KW) association test revealed three main chromosome regions related to YPC (Figure 1). The largest is located on chromosome 2Hch where the majority of markers showed an association with YPC (Figure 1). Smaller regions were detected on chromosomes 3Hch and 7Hch. Candidate genes Ggpps1, Zds, Hyd3, Ppo1, e-Lcy and Psy1 showed a significant association with YPC (Figure 1). The MQM analysis resulted in a significant QTL at the distal part of chromosome 2Hch between 207 and 229 cM (p<0.05) where no carotenoid-related genes were mapped in this work.


Macrocolinearity between H. chilense and H. vulgare

Comparative analysis of the twelve candidate genes positions in H. chilense and barley using the Barley Genome Zipper [56] revealed a good agreement between both species for the candidate genes selected (Table 3). Indeed, chromosome location and relative positions of genes within chromosomes were conserved in all cases. Regarding Zds, its position could not be established in barley since the orthologous genes from rice, sorghum or Brachypodium were not found in the Barley Genome Zipper [56]. However, the close linkage between Zds and Ggpps1 in H. chilense suggests that the two genes are located in equivalent positions in barley. This is supported by the high-resolution comparative analysis between barley and rice performed by [56]. Briefly, the Barley Genome Zipper establishes the putative linear order of 21,766 barley genes by integrating gene indices of rice, sorghum and Brachypodium[56] and allows the establishment of the synteny relations between barley and rice chromosomes based on the position of the putative orthologs in both species. Chromosome 2H in barley corresponds to chromosome 4R in rice, except for a region in 2HS arm which is equivalent to 7R. In barley the region near the 2H centromere shows significant matches to both 7RS (where Zds is located in rice) and 7RL (where Ggpps1 is located in rice). This is in agreement with H. chilense results and suggests that Zds would be located in an equivalent position in barley.

An apparent break in the synteny between H. chilense and H. vulgare happens for Psy1 which is located in 7HL in barley and in 7Hchα in H. chilense[31]. However, genetic mapping could not establish the relative position of Psy1 in 7Hch chromosome since it remained in a short linkage group not linked to 7Hch chromosome. Thus, its putative location in 7Hchα is based upon physical mapping using a telosomic addition line. We have recently observed a reorganization of the H. chilense chromatin in wheat background between different chromosomes (A. Martín, personal communication). Thus, a translocation involving Psy1 and 7HchS during the development of the addition line cannot be totally excluded and further work is required to confirm the position of Psy1 in the chromosome 7Hch.

YPC regions: comparative analysis between H. chilenseand wheat

The association study for YPC allowed the identification of three main regions in chromosomes 2Hch, 3Hch and 7Hch for YPC variation in H. chilense as revealed by a KW association test. Despite a single QTL at the distal part of chromosome 2HchL being above the significance threshold established, all three regions were considered significant since the population size critically affects the power of QTL detection and the precision of QTL estimates [58]. For instance, QTLs with small effects for stripe rust resistance in barley were detected only by increasing the population size [59]. The significance threshold must thus be chosen according to the population size and the trait of interest [58]. Therefore, we relied on KW-defined regions and considered the QTL analyses to conclude that the distal part of chromosome 2Hch was the most significant one. Seven of the candidate genes were not associated with YPC in this work. This may indicate that they do not contribute to YPC variation in this population. Alternatively, these genes might have a minor effect which cannot be detected with this population size.

The region located in chromosome 3Hch includes the e Lcy gene, whose role in YPC has been demonstrated in hexaploid wheat and maize. In wheat, e Lcy co-localized with a QTL for lutein accumulation and a specific mutation causing lutein content variations was identified [35]. This QTL was located in the proximal 3BS region this being the position of this gene in hexaploid wheat in agreement with the results obtained in H. chilense. Similarly, it has been shown that a QTL for carotenoid accumulation in maize chromosome 8 co-locates with e Lcy gene [25, 26].

The distal part of chromosome 7HchL is also related to YPC in H. chilense. The importance of this region has been clearly demonstrated in wheat, as a result of variations in Psy1 genes [32, 33, 38]. This has promoted extensive work towards the identification of Psy1 A and Psy1 B alleles, the determination of their role in YPC and the development of functional markers for selection [34, 60, 61]. Furthermore, there is evidence of an additional locus for YPC in the distal part of chromosome 7AL in durum wheat [38]. Given that Psy1 is apparently located in the 7Hchα arm, this might indicate that an additional locus is found at 7HchL, in agreement with durum wheat results. Nevertheless, since genetic mapping did not resolve Psy1 position within chromosome 7Hch, we cannot totally discard the occurrence of a translocation 7HchL/7HchS during the development of the wheat/H. chilense chromosome addition line. Thus, macrocolinearity cannot be established for this gene at present and the YPC region on chromosome 7HchL might possibly be related to Psy1 variation. Indeed, Psy1 showed a low association with YPC (p<0.1).

Finally, there is a region on chromosome 2Hch related to YPC which extends over the 80% of the chromosomal length. Four candidate genes, Ggpps1, Zds, Hyd3 and Ppo1, are mapped within this interval. The most significant zone within this region is located in the distal part of chromosome 2HchL (Figure 1). However, the complete KW-defined region must be considered as a target since the population size is probably hampering the determination of other QTLs in this chromosome. Indeed, in a preliminary map constructed using a H1×H7 F2 population, which did not cover the distal part of chromosome 2Hch, a QTL for YPC was detected in the chromosome 2Hch in the vicinity of the marker IAS pHc2 1[62] which is now mapped at 48 cM (Figure 1). Additionally, the location of four carotenoid-related genes in this area further supports the importance of this region for YPC.

The relevance of chromosome 2A for YPC and/or carotenoid content has been previously reported in wheat. Most works have focused on the role of polyphenol oxidases since these enzymes cause the darkening of flour, pasta and noodle products [63]. Duplicated polyphenol oxidase genes (Ppo1 and Ppo2) have been identified and mapped clustered in barley 2H chromosome [64]. Although only Ppo1 was mapped in H. chilense, a tightly linked Ppo2 may be expected. In any case, the association of Ppo1 and YPC in H. chilense seems to indicate the occurrence of darkening processes in this species. Similarly, the role of Ppo A1 and Ppo D1 has been extensively studied in wheat including mapping studies [65, 66], the development of functional markers [6769] and the cloning and analysis of these genes [70, 71]. Recently, duplicated Ppo genes (Ppo A2, Ppo B2 and Ppo D2) have been identified [72] and mapped to chromosomes 2A, 2B and 2D [73]. Thus the results obtained in H. chilense are in agreement with previous findings in wheat.

Our results also suggest the potential importance of the centromeric region on chromosome 2Hch for YPC. QTL and association mapping studies have identified regions for YPC or carotenoid content in chromosome 2A [32, 33, 74]. Recently, a QTL on the centromeric region of chromosome 2A has been reported [33]. However, it could not be associated with YPC per se since the markers within the confidence interval were related to kernel weight variation. Thus, it was proposed that this QTL may be associated with yellow pigment concentration due to a lower carbohydrate content in smaller grains or it could be linked to a QTL for kernel weight [33]. Since there is no significant association between YPC and kernel weight in H. chilense[42], this region does not seem to be related to carotenoid concentration. Moreover, previous findings in durum wheat also support the existence of a QTL for YPC in this region [32, 74]. Both studies showed the association between Xgwm495 and YPC using a mapping population derived from the cross W9262-260D3 × Kofa [32] and a collection of 93 diverse accessions of durum wheat [74]. This marker is located in the arm 2AS (C-2AS5-078 bin) at 108.5 cM [75] (see Group 2 data file at between markers Xgwm372 (C-2AS5-078 bin, at 90.8 cM) and Xgwm249 (C-2AL-1-0.85 bin, at 111.9 cM). Both Xgwm372 and Xgwm249 are within the confidence interval for the QTL on chromosome 2A reported by [33]. Hence, all three works identify the same region around the centromere of chromosome 2A, and thus, this region seems to be effectively related to YPC and/or carotenoid content in durum wheat. The results presented in this work also support the importance of the centromeric region of the chromosome 2Hch in YPC. Furthermore, the Zds and Ggpps1 genes were mapped within this region, and they should therefore be considered in durum wheat. The potential association of Zds with YPC in durum wheat has already been hypothesized after physical mapping on chromosomes 2A and 2B [76]. Later studies cloned Zds gene in common wheat [77] and identified a QTL for YPC related to Zds D1 variation in chromosome 2D in common wheat [78]. Similarly, the co-localization of Zds with a QTL for carotenoid content in chromosome 7 of maize [25] also supports the potential role of this gene in grasses. Similarly, the association between Ggpps1 expression and the carotenoid content in maize [29] and the close linkage between Zds and Ggpps1 in H. chilense make the latter an interesting candidate gene for durum wheat studies. Likewise, variations at Hyd3 locus are important for maize endosperm carotenoid content [28, 79]. Given the association of this gene with YPC and its position in H. chilense map, Hyd3 should be also considered in further studies in durum wheat.

The most significant region of 2Hch, as identified by MQM analysis, is located in the distal part of the chromosome 2HchL where no candidate genes were located in this work. The occurrence of this association can be explained by several hypotheses, although they are all very speculative. The simplest one is that other carotenoid genes not considered in this study are located in the distal 2HchL. A second possibility would be that genes for carotenoid esterification are located in this region. A QTL for lutein esters was identified in chromosome 2B [35]. It is flanked by the marker KsuD22 which has been located in the chromosome 2BL by deletion mapping [75]. Esterification is a common mechanism for sequestering carotenoids in plants [80]. Indeed, carotenoids are accumulated in specialized lipoprotein-sequestering structures in the chromoplasts [81] and the apolar compounds of some chromoplasts, such as fibrils, are mainly composed of esterified xanthophylls [81]. H. chilense genome addition in tritordeums produces both high carotenoid content and an increase in lutein esterification [10], and, thus, the presence of genes for differential esterification ability in the 2HchL chromosome might be considered in the future.

The lack of association between the rest of the candidate genes (Dxr, Hdr, Ccd1, b Lcy, Pds, Psy2 and Psy3) and YPC in H. chilense suggests at least two possibilities: (1) these genes are not related with YPC variation in the population; (2) they have minor effects which cannot be detected with the current population size. With the results presented in this work it is not possible to discern between these possibilities. While Psy2 and Psy3 are not associated with seed carotenoid content in other grasses (reviewed by [82]) and thus, they may be discarded for further analyses, the rest of the genes might be still useful for durum wheat studies. For instance, Ccd1 copy number is negatively correlated with carotenoid content in maize [83]. It is mapped in the distal part of 5HchS in concordance with QTLs for carotenoid content and YPC in durum wheat [33, 84]. Thus, it may be an interesting candidate gene for durum wheat despite the lack of association with YPC in this work.


The equivalent location of the carotenoid-related genes in H. chilense and barley shows a high level of collinearity between both species, at least for the genes studied in this work. Considering the high synteny among Triticeae species along with the high YPC content of H. chilense and its derived amphiploids (tritordeums), the Hch genome constitutes a valuable tool for YPC and carotenoid content studies in the Triticeae. Indeed, the YPC regions detected in H. chilense showed good agreement with previous findings in wheat. Accordingly, the location of Zds and Ggpps1 within one of these regions around the 2Hch centromere is in concordance with QTL for YPC and carotenoid content in wheat, and suggests that both genes should be considered for durum wheat improvement. In addition, the identification and mapping of the candidate genes in H. chilense will enable further studies to investigate the genetic basis of the high YPC/carotenoid content in tritordeum which could also be extrapolated to durum wheat.


Dxr :

1-deoxy-D-xylulose 5-phosphate reductoisomerase

Hdr synonym ispH:

4-hydroxy-3-methylbut-2-enyl diphosphate reductase


Automatic cofactor selection

Hyd3 Beta :

-carotene hydroxylase 3

Ccd1 :

Cleavage dioxygenase 1 gene


Cleaved Amplified Polymorphism


Diversity Arrays Technology

Ggpps1 :

Geranyl geranyl pyrophosphate synthase


Interval Mapping



b-Lcy Lycopene beta:



Lycopene epsilon cyclase


Methylerythritol phosphate


Monte Carlo Maximum Likelihood Mapping algorithm


Multiple QTL Mapping

Pds :

Phytoene dehydrogenase

Psy2 :

Phytoene synthase 2

Psy3 :

Phytoene synthase 3

Ppo1 :

Polyphenol oxidase 1 gene


Quantitative trait locus


Recombinant Inbred Lines


Single Nucleotide Polymorphisms


Yellow pigment content

Zds Zeta :

-carotene desaturase.


  1. Martin AC, Atienza SG, Ramirez MC, Barro F, Martin A: Male fertility restoration of wheat in Hordeum chilense cytoplasm is associated with 6H(ch)S chromosome addition. Aust J Agric Res. 2008, 59: 206-213. 10.1071/AR07239.

    Article  CAS  Google Scholar 

  2. Martin AC, Atienza SG, Ramirez MC, Barro F, Martin A: Chromosome engineering in wheat to restore male fertility in the msH1 CMS system. Mol Breed. 2009, 24: 397-408. 10.1007/s11032-009-9301-z.

    Article  CAS  Google Scholar 

  3. Martín AC, Atienza SG, Ramírez M, Barro F, Martin A: Molecular and cytological characterization of an extra acrocentric chromosome that restores male fertility of wheat in the msH1 CMS system. Theor Appl Genet. 2010, 121: 1093-1101. 10.1007/s00122-010-1374-x.

    Article  PubMed  Google Scholar 

  4. Alvarez JB, Martin LM, Martin A: Chromosomal localization of genes for carotenoid pigments using addition lines of Hordeum chilense in wheat. Plant Breed. 1998, 117: 287-289. 10.1111/j.1439-0523.1998.tb01942.x.

    Article  CAS  Google Scholar 

  5. Martin A, Martínez C, Rubiales D, Ballesteros J: Tritordeum: triticale's new brother cereal. Triticale: today and tomorrow. Edited by: Güedes-Pinto H, Darvey N, Carnide VP. 1996, Dordrecht, NL: Kluwer Academic Publishers, 57-72.

    Chapter  Google Scholar 

  6. Rodríguez-Suárez C, Giménez MJ, Ramírez MC, Martín AC, Gutierrez N, Ávila CM, Martín A, Atienza SG: Exploitation of nuclear and cytoplasm variability in Hordeum chilense for wheat breeding. Plant Genet Res Charact Utiliz. 2011, 9: 313-316.

    Article  Google Scholar 

  7. Martin A, Chapman V: A hybrid between Hordeum chilense and Triticum aestivum. Cereal Res Commun. 1977, 5: 365-368.

    Google Scholar 

  8. Martin A, Sánchez-Monge Laguna E: Cytology and morphology of the amphiploid Hordeum chilense × Triticum turgidum conv durum. Euphytica. 1982, 31: 261-267. 10.1007/BF00028329.

    Article  Google Scholar 

  9. Martin A, Alvarez JB, Martin LM, Barro F, Ballesteros J: The development of tritordeum: a novel cereal for food processing. J Cereal Sci. 1999, 30: 85-95. 10.1006/jcrs.1998.0235.

    Article  Google Scholar 

  10. Atienza SG, Ballesteros J, Martin A, Hornero-Mendez D: Genetic variability of carotenoid concentration and degree of esterification among tritordeum (xTritordeum Ascherson et Graebner) and durum wheat accessions. J Agric Food Chem. 2007, 55: 4244-4251. 10.1021/jf070342p.

    Article  PubMed  CAS  Google Scholar 

  11. Digesù AM, Platani C, Cattivelli L, Mangini G, Blanco A: Genetic variability in yellow pigment components in cultivated and wild tetraploid wheats. J Cereal Sci. 2009, 50: 210-218. 10.1016/j.jcs.2009.05.002.

    Article  Google Scholar 

  12. Hentschel V, Kranl K, Hollmann J, Lindhauer MG, Bohm V, Bitsch R: Spectrophotometric determination of yellow pigment content and evaluation of carotenoids by high-performance liquid chromatography in durum wheat grain. J Agric Food Chem. 2002, 50: 6663-6668. 10.1021/jf025701p.

    Article  PubMed  CAS  Google Scholar 

  13. Leenhardt F, Lyan B, Rock E, Boussard A, Potus J, Chanliaud E, Remesy C: Genetic variability of carotenoid concentration, and lipoxygenase and peroxidase activities among cultivated wheat species and bread wheat varieties. Eur J Biochem. 2006, 25: 170-176.

    CAS  Google Scholar 

  14. Al-Delaimy WK, Slimani N, Ferrari P, Key T, Spencer E, Johansson I, Johansson G, Mattisson I, Wirfalt E, Sieri S, et al: Plasma carotenoids as biomarkers of intake of fruits and vegetables: ecological-level correlations in the European Prospective Investigation into Cancer and Nutrition (EPIC). Eur J Clin Nutr. 2005, 59: 1397-1408. 10.1038/sj.ejcn.1602253.

    Article  PubMed  CAS  Google Scholar 

  15. Nishino H, Murakoshi M, Tokuda H, Satomi Y: Cancer prevention by carotenoids. Arch Biochem Biophys. 2009, 483: 165-168. 10.1016/

    Article  PubMed  CAS  Google Scholar 

  16. Giuliano G, Tavazza R, Diretto G, Beyer P, Taylor MA: Metabolic engineering of carotenoid biosynthesis in plants. Trends Biotechnol. 2008, 26: 139-145. 10.1016/j.tibtech.2007.12.003.

    Article  PubMed  CAS  Google Scholar 

  17. Carpentier S, Knaus M, Suh M: Associations between lutein, zeaxanthin, and age-related macular degeneration: An overview. Crit Rev Food Sci Nutr. 2009, 49: 313-326. 10.1080/10408390802066979.

    Article  PubMed  CAS  Google Scholar 

  18. Fraser PD, Bramley PM: The biosynthesis and nutritional uses of carotenoids. Prog Lipid Res. 2004, 43: 228-265. 10.1016/j.plipres.2003.10.002.

    Article  PubMed  CAS  Google Scholar 

  19. Cuttriss A, Mimica J, Howitt C, Pogson B: Carotenoids. The structure and function of plastids. Edited by: Wise RR, Hoober JK, Dordrecht . 2006, TheNetherlands: Springer, 315-334.

    Chapter  Google Scholar 

  20. Hirschberg J: Carotenoid biosynthesis in flowering plants. Curr Opin Plant Biol. 2001, 4: 210-218. 10.1016/S1369-5266(00)00163-1.

    Article  PubMed  CAS  Google Scholar 

  21. Howitt CA, Pogson BJ: Carotenoid accumulation and function in seeds and non-green tissues. Plant Cell Environ. 2006, 29: 435-445. 10.1111/j.1365-3040.2005.01492.x.

    Article  PubMed  CAS  Google Scholar 

  22. Matthews PD, Wurtzel ET: Biotechnology of food colorant production. Food Colorants: Chemical and Functional Properties. Edited by: Socaciu C. 2007, Boca Raton, FL: CRC Press, 347-398.

    Google Scholar 

  23. Buckner B, San Miguel P, Janick-Buckner D, Bennetzen JL: The y1 gene of maize codes for phytoene synthase. Genetics. 1996, 143: 479-488.

    PubMed  CAS  PubMed Central  Google Scholar 

  24. Gallagher CE, Matthews PD, Li F, Wurtzel ET: Gene duplication in the carotenoid biosynthetic pathway preceded evolution of the grasses. Plant Physiol. 2004, 135: 1776-1783. 10.1104/pp.104.039818.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  25. Wong JC, Lambert RJ, Wurtzel ET, Rocheford TR: QTL and candidate genes phytoene synthase and zeta-carotene desaturase associated with the accumulation of carotenoids in maize. Theor Appl Genet. 2004, 108: 349-359. 10.1007/s00122-003-1436-4.

    Article  PubMed  CAS  Google Scholar 

  26. Harjes CE, Rocheford TR, Bai L, Brutnell TP, Kandianis CB, Sowinski SG, Stapleton AE, Vallabhaneni R, Williams M, Wurtzel ET, et al: Natural genetic variation in lycopene epsilon cyclase tapped for maize biofortification. Science. 2008, 319: 330-333. 10.1126/science.1150255.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  27. Li F, Murillo C, Wurtzel ET: Maize Y9 encodes a product essential for 15-cis-{zeta}-carotene isomerization. Plant Physiol. 2007, 144: 1181-1189. 10.1104/pp.107.098996.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  28. Vallabhaneni R, Gallagher CE, Licciardello N, Cuttriss AJ, Quinlan RF, Wurtzel ET: Metabolite sorting of a germplasm collection reveals the hydroxylase3 locus as a new target for maize provitamin A biofortification. Plant Physiol. 2009, 151: 1635-1645. 10.1104/pp.109.145177.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  29. Vallabhaneni R, Wurtzel ET: Timing and biosynthetic potential for carotenoid accumulation in genetically diverse germplasm of maize. Plant Physiol. 2009, 150: 562-572. 10.1104/pp.109.137042.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  30. Fraser PD, Truesdale MR, Bird CR, Schuch W, Bramley PM: Carotenoid biosynthesis during tomato fruit development (evidence for tissue-specific gene expression). Plant Physiol. 1994, 105: 405-413.

    PubMed  CAS  PubMed Central  Google Scholar 

  31. Atienza SG, Avila CM, Martin A: The development of a PCR-based marker for Psy1 from Hordeum chilense, a candidate gene for carotenoid content accumulation in tritordeum seeds. Austr J Agric Res. 2007, 58: 767-773. 10.1071/AR06338.

    Article  CAS  Google Scholar 

  32. Pozniak CJ, Knox RE, Clarke FR, Clarke JM: Identification of QTL and association of a phytoene synthase gene with endosperm colour in durum wheat. Theor Appl Genet. 2007, 114: 525-537. 10.1007/s00122-006-0453-5.

    Article  PubMed  CAS  Google Scholar 

  33. Blanco A, Colasuonno P, Gadaleta A, Mangini G, Schiavulli A, Simeone R, Digesù AM, De Vita P, Mastrangelo AM, Cattivelli L: Quantitative trait loci for yellow pigment concentration and individual carotenoid compounds in durum wheat. J Cereal Sci. 2011, 54: 255-264. 10.1016/j.jcs.2011.07.002.

    Article  CAS  Google Scholar 

  34. He XY, Zhang YL, He ZH, Wu YP, Xiao YG, Ma CX, Xia XC: Characterization of phytoene synthase 1 gene (Psy1) located on common wheat chromosome 7A and development of a functional marker. Theor Appl Genet. 2008, 116: 213-221. 10.1007/s00122-007-0660-8.

    Article  PubMed  CAS  Google Scholar 

  35. Howitt CA, Cavanagh CR, Bowerman AF, Cazzonelli C, Rampling L, Mimica JL, Pogson BJ: Alternative splicing, activation of cryptic exons and amino acid substitutions in carotenoid biosynthetic genes are associated with lutein accumulation in wheat endosperm. Func Integr Genomics. 2009, 9: 363-376. 10.1007/s10142-009-0121-3.

    Article  CAS  Google Scholar 

  36. Singh A, Reimer S, Pozniak CJ, Clarke FR, Clarke JM, Knox RE, Singh AK: Allelic variation at Psy1-A1 and association with yellow pigment in durum wheat grain. Theor Appl Genet. 2009, 118: 1539-1548. 10.1007/s00122-009-1001-x.

    Article  PubMed  CAS  Google Scholar 

  37. Zhang W, Chao S, Manthey F, Chicaiza O, Brevis JC, Echenique V, Dubcovsky J: QTL analysis of pasta quality using a composite microsatellite and SNP map of durum wheat. Theor Appl Genet. 2008, 117: 1361-1377. 10.1007/s00122-008-0869-1.

    Article  PubMed  CAS  Google Scholar 

  38. Zhang W, Dubcovsky J: Association between allelic variation at the Phytoene synthase 1 gene and yellow pigment content in the wheat grain. Theor Appl Genet. 2008, 116: 635-645. 10.1007/s00122-007-0697-8.

    Article  PubMed  CAS  Google Scholar 

  39. Zhang YL, Wu YP, Xiao YG, He ZH, Zhang Y, Yan J, Xia XC, Ma CX: QTL mapping for flour and noodle colour components and yellow pigment content in common wheat. Euphytica. 2009, 165: 435-444. 10.1007/s10681-008-9744-z.

    Article  CAS  Google Scholar 

  40. Bolot S, Abrouk M, Masood-Quraishi U, Stein N, Messing J, Feuillet C, Salse J: The ‘inner circle’ of the cereal genomes. Curr Opin Plant biol. 2009, 12: 119-125. 10.1016/j.pbi.2008.10.011.

    Article  PubMed  CAS  Google Scholar 

  41. Devos KM: Updating the 'Crop Circle'. Curr Opin Plant Biol. 2005, 8: 155-162. 10.1016/j.pbi.2005.01.005.

    Article  PubMed  CAS  Google Scholar 

  42. Alvarez JB, Martin LM, Martin A: Genetic variation for carotenoid pigment content in the amphiploid Hordeum chilense x Triticum turgidum conv. durum. Plant Breed. 1999, 118: 187-189. 10.1046/j.1439-0523.1999.118002187.x.

    Article  CAS  Google Scholar 

  43. Atienza SG, Avila CM, Ramirez MC, Martin A: Application of near infrared reflectance spectroscopy to the determination of carotenoid content in tritordeum for breeding purposes. Austr J Agric Res. 2005, 56: 85-89. 10.1071/AR04154.

    Article  CAS  Google Scholar 

  44. Pudoc Broertjes C, Miller TE, Reader SM, Chapman V: The addition of Hordeum chilense chromosomes to wheat. Induced variability in plant breeding. 1982, Wageningen, The Netherlands: Proceedings of the InternationalEucarpia Symposium, 79-81.

    Google Scholar 

  45. Cherif-Mouaki S, Said M, Alvarez JB, Cabrera A: Sub-arm location of prolamin and EST-SSR loci on chromosome 1Hch from Hordeum chilense. Euphytica. 2011, 178: 63-69. 10.1007/s10681-010-0268-y.

    Article  CAS  Google Scholar 

  46. Said M, Cabrera A: A physical map of chromosome 4H(ch) from H. chilense containing SSR, STS and EST-SSR molecular markers. Euphytica. 2009, 167: 253-259. 10.1007/s10681-009-9895-6.

    Article  CAS  Google Scholar 

  47. Rodríguez-Suárez C, Giménez MJ, Gutiérrez N, Ávila CM, Machado A, Huttner E, Ramírez MC, Martín A, Castillo A, Kilian A, et al: Development of wild barley (Hordeum chilense)-derived DArT markers and their use into genetic and physical mapping. Theor Appl Genet. 2012, 124: 713-722. 10.1007/s00122-011-1741-2.

    Article  PubMed  Google Scholar 

  48. Murray YHG, Thompson WF: Rapid isolation of high molecular weight plant DNA. Nucleic Acids Res. 1980, 8: 4321-4326. 10.1093/nar/8.19.4321.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  49. Rodríguez-Suárez C, Atienza SG, Pistón F: Allelic variation, alternative splicing and expression analysis of Psy1 gene in Hordeum chilense Roem. et Schult. PLoS One. 2011, 6: e19885-10.1371/journal.pone.0019885.

    Article  PubMed  PubMed Central  Google Scholar 

  50. Untergasser A, Nijveen H, Rao X, Bisseling T, Geurts R, Leunissen JAM: Primer3Plus, an enhanced web interface to Primer3. Nucleic Acids Res. 2007, 35: W71-W74. 10.1093/nar/gkm306.

    Article  PubMed  PubMed Central  Google Scholar 

  51. AACC: AACC Method 14–50. 1997

    Google Scholar 

  52. Van Ooijen JW: Joinmap 4.0®, Software for the calculation of genetic linkage maps in experimental populations. Edited by: Kiazma BW. 2006, Wageningen The Netherlands: Plant Research International.

    Google Scholar 

  53. Van Ooijen JW, Boer MP, Jansen RC, Maliepaard C: MapQTLTM version 4.0: Software for the calculation of QTL positions on genetic maps. Edited by: Kiazma BW. 2000, Wageningen, The Netherlands: Plant Research International.

    Google Scholar 

  54. Van Ooijen JW: Accuracy of mapping quantitative trait loci in autogamous species. Theor Appl Genet. 1992, 84: 803-811.

    Article  PubMed  CAS  Google Scholar 

  55. Voorrips RE: MapChart: Software for the graphical presentation of linkage maps and QTLs. J Hered. 2002, 93: 77-78. 10.1093/jhered/93.1.77.

    Article  PubMed  CAS  Google Scholar 

  56. Mayer KFX, Martis M, Hedley PE, Šimková H, Liu H, Morris JA, Steuernagel B, Taudien S, Roessner S, Gundlach H, et al: Unlocking the barley genome by chromosomal and comparative genomics. Plant Cell. 2011, 23: 1249-1263. 10.1105/tpc.110.082537.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  57. Close T, Bhat P, Lonardi S, Wu Y, Rostoks N, Ramsay L, Druka A, Stein N, Svensson J, Wanamaker S, et al: Development and implementation of high-throughput SNP genotyping in barley. BMC Genomics. 2009, 10: 582-10.1186/1471-2164-10-582.

    Article  PubMed  PubMed Central  Google Scholar 

  58. Schön CC, Utz HF, Groh S, Truberg B, Openshaw S, Melchinger AE: Quantitative trait locus mapping based on resampling in a vast maize testcross experiment and its relevance to quantitative genetics or complex traits. Genetics. 2004, 167: 485-498. 10.1534/genetics.167.1.485.

    Article  PubMed  PubMed Central  Google Scholar 

  59. Vales MI, Schön CC, Capettini F, Chen XM, Corey AE, Mather DE, Mundt CC, Richardson KL, Sandoval-Islas JS, Utz HF, et al: Effect of pupulation size on the estimation of QTL: a test using resistance to barley stripe rust. Theor Appl Genet. 2005, 111: 1260-1270. 10.1007/s00122-005-0043-y.

    Article  PubMed  CAS  Google Scholar 

  60. He XY, He ZH, Ma W, Appels R, Xia XC: Allelic variants of phytoene synthase 1 (Psy1) genes in Chinese and CIMMYT wheat cultivars and development of functional markers for flour colour. Mol Breed. 2009, 23: 553-563. 10.1007/s11032-009-9255-1.

    Article  CAS  Google Scholar 

  61. He XY, Wang JW, Ammar K, Pena RJ, Xia XC, He ZH: Allelic variants at the Psy-A1 and Psy-B1 loci in durum wheat and their associations with grain yellowness. Crop Sci. 2009, 49: 2058-2064. 10.2135/cropsci2008.11.0651.

    Article  CAS  Google Scholar 

  62. Atienza SG, Ramirez CM, Hernandez P, Martin A: Chromosomal location of genes for carotenoid pigments in Hordeum chilense. Plant Breed. 2004, 123: 303-304. 10.1111/j.1439-0523.2004.00918.x.

    Article  CAS  Google Scholar 

  63. McIntosh RA, Yamazaki Y, Dubcovsky J, Rogers J, Morris C, Somers DJ, Appels R, Devos KM: Catalogue of gene symbols for wheat.

  64. Taketa S, Matsuki K, Amano S, Saisho D, Himi E, Shitsukawa N, Yuo T, Noda K, Takeda K: Duplicate polyphenol oxidase genes on barley chromosome 2H and their functional differentiation in the phenol reaction of spikes and grains. J Exp Bot. 2010, 61: 3983-3993. 10.1093/jxb/erq211.

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  65. Jimenez M, Dubcovsky J: Chromosome location of genes affecting polyphenol oxidase activity in seeds of common and durum wheat. Plant Breed. 1999, 118: 395-398. 10.1046/j.1439-0523.1999.00393.x.

    Article  CAS  Google Scholar 

  66. Mares DJ, Campbell AW: Mapping components of flour colour in Australian wheat. Austr J Agric Res. 2001, 52: 1297-1309. 10.1071/AR01048.

    Article  CAS  Google Scholar 

  67. He XY, He ZH, Zhang LP, Sun DJ, Morris CF, Fuerst EP, Xia XC: Allelic variation of polyphenol oxidase (PPO) genes located on chromosomes 2A and 2D and development of functional markers for the PPO genes in common wheat. Theor Appl Genet. 2007, 115: 47-58. 10.1007/s00122-007-0539-8.

    Article  PubMed  CAS  Google Scholar 

  68. Sun D, He Z, Xia X, Zhang L, Morris C, Appels R, Ma W, Wang H: A novel STS marker for polyphenol oxidase activity in bread wheat. Mol Breed. 2005, 16: 209-218. 10.1007/s11032-005-6618-0.

    Article  CAS  Google Scholar 

  69. Chang C, Zhang H-P, Xu J, You M-S, Li B-Y, Liu G-T: Variation in two PPO genes associated with polyphenol oxidase activity in seeds of common wheat. Euphytica. 2007, 154: 181-193. 10.1007/s10681-006-9285-2.

    Article  CAS  Google Scholar 

  70. He XY, He ZH, Morris CF, Xia XC: Cloning and phylogenetic analysis of polyphenol oxidase genes in common wheat and related species. Genet Res Crop Evol. 2009, 56: 311-321. 10.1007/s10722-008-9365-3.

    Article  CAS  Google Scholar 

  71. Sun YW, He ZH, Ma WJ, Xia XC: Alternative splicing in the coding region of Ppo-A1 directly influences the polyphenol oxidase activity in common wheat (Triticum aestivum L.). Funct Integr Genomics. 2011, 11: 85-93. 10.1007/s10142-010-0201-4.

    Article  PubMed  CAS  Google Scholar 

  72. Beecher B, Skinner DZ: Molecular cloning and expression analysis of multiple polyphenol oxidase genes in developing wheat (Triticum aestivum) kernels. J Cereal Sci. 2011, 53: 371-378. 10.1016/j.jcs.2011.01.015.

    Article  CAS  Google Scholar 

  73. Beecher B, Carter A, See D: Genetic mapping of new seed-expressed polyphenol oxidase genes in wheat (Triticum aestivum L.). Theor Appl Genet. 2012, 124: 1463-1473. 10.1007/s00122-012-1801-2.

    Article  PubMed  CAS  Google Scholar 

  74. Reimer S, Pozniak CJ, Clarke FR, Clarke JM, Somers DJ, Knox RE, Singh AK: Association mapping of yellow pigment in an elite collection of durum wheat cultivars and breeding lines. Genome. 2008, 51: 1016-1025. 10.1139/G08-083.

    Article  PubMed  CAS  Google Scholar 

  75. Sourdille P, Singh S, Cadalen T, Brown-Guedira GL, Gay G, Qi L, Gill BS, Dufour P, Murigneux A, Bernard M: Microsatellite-based deletion bin system for the establishment of genetic-physical map relationships in wheat (Triticum aestivum L.). Func Integr Genomics. 2004, 4: 12-25. 10.1007/s10142-004-0106-1.

    Article  CAS  Google Scholar 

  76. Cenci A, Somma S, Chantret N, Dubcovsky J, Blanco A: PCR identification of durum wheat BAC clones containing genes coding for carotenoid biosynthesis enzymes and their chromosome localization. Genome. 2004, 47: 911-917. 10.1139/g04-033.

    Article  PubMed  CAS  Google Scholar 

  77. Cong L, Wang C, Chen L, Liu H, Yang G, He G: Expression of phytoene synthase1 and carotene desaturase crtI genes result in an increase in the total carotenoids content in transgenic elite wheat (Triticum aestivum L.). J Agric Food Chem. 2009, 57: 8652-8660. 10.1021/jf9012218.

    Article  PubMed  CAS  Google Scholar 

  78. Zhang CY, Dong CH, He XY, Zhang LP, Xia XC, He ZH: Allelic variants at the TaZds-D1 locus on wheat chromosome 2DL and their association with yellow pigment content. Crop Sci. 2011, 51: 1580-1590. 10.2135/cropsci2010.12.0689.

    Article  CAS  Google Scholar 

  79. Yan JB, Kandianis CB, Harjes CE, Bai L, Kim EH, Yang XH, Skinner DJ, Fu ZY, Mitchell S, Li Q, et al: Rare genetic variation at Zea mays crtRB1 increases beta-carotene in maize grain. Nature Genet. 2010, 42: 322-U374. 10.1038/ng.551.

    Article  PubMed  CAS  Google Scholar 

  80. Hornero-Mendez D, Minguez-Mosquera MI: Xanthophyll esterification accompanying carotenoid overaccumulation in chromoplast of Capsicum annuum ripening fruits is a constitutive process and useful for ripeness index. J Agric Food Chem. 2000, 48: 1617-1622. 10.1021/jf9912046.

    Article  PubMed  CAS  Google Scholar 

  81. Vishnevetsky M, Ovadis M, Vainstein A: Carotenoid sequestration in plants: the role of carotenoid-associated proteins. Trends Plant Sci. 1999, 4: 232-235. 10.1016/S1360-1385(99)01414-4.

    Article  PubMed  Google Scholar 

  82. Rodríguez-Suárez C, Giménez MJ, Atienza SG: Progress and perspectives for carotenoid accumulation in selected Triticeae species. Crop Pasture Sci. 2010, 61: 743-751. 10.1071/CP10025.

    Article  Google Scholar 

  83. Vallabhaneni R, Bradbury LMT, Wurtzel ET: The carotenoid dioxygenase gene family in maize, sorghum, and rice. Arch Biochem Biophys. 2010, 504: 104-111. 10.1016/

    Article  PubMed  CAS  PubMed Central  Google Scholar 

  84. Roncallo P, Cervigni GL, Jensen C, Miranda R, Carrera AD, Helguera M, Echenique V: QTL analysis of main and epistatic effects for flour color traits in durum wheat. Euphytica. 2012, 185 (1): 77-92. 10.1007/s10681-012-0628-x.

    Article  Google Scholar 

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This research was supported by grants (to S.G. Atienza) AGL2011-24399 and P09-AGR-4817 from the Ministerio de Economía y Competitividad, Junta de Andalucía and FEDER. We are grateful to E. León and A. Pozo for their technical assistance and to C.M. Avila for the critical review of this manuscript. C. Rodríguez-Suárez acknowledges financial support from CSIC (JAE-Doc program). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

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Correspondence to Sergio G Atienza.

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The authors declare that they have no competing interests.

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CR-S and SGA conceived and designed the study. CR-S performed the experiments. SGA performed the QTL analyses. CR-S and SGA analyzed the data and wrote the paper. Both authors have read and approved the final manuscript.

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Additional file 1: Table S1. Accession numbers of the sequences used for alignments in the design of primers for amplification of the orthologous genes in H. chilense.(DOCX 13 KB)

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Rodríguez-Suárez, C., Atienza, S.G. Hordeum chilense genome, a useful tool to investigate the endosperm yellow pigment content in the Triticeae. BMC Plant Biol 12, 200 (2012).

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