Systems approach for exploring the intricate associations between sweetness, color and aroma in melon fruits

Table 2 Gene-metabolite correlation values between alcohol acyl-transferases versus experimental evidence for their metabolic association

Ester product	ID accession*	*Cm-AAT1* (MELO3C024771)		*Cm-AAT2* (MELO3C024766)
Ester product	ID accession*	Rho correlation coefficient ( p value)ζ	Production levels in vitro§	Rho correlation coefficient ( p value)ζ	Production levels in vitro§
Butyl acetate	AE7	0.34 (0.0009)	High	NS	ND
Hexyl acetate	AE8	0.29 (0.004)	High	NS	ND
2-methylpropyl acetate acetate	AE6	0.34 (0.0008)	Low	NS	ND
Benzyl acetate	AE2	0.28 (0.006)	High	NS	ND
Cinnamyl acetate	AE1	0.41 (3.43e-05)	Medium	NS	ND
Ethyl phenyl acetate	EE15	NS	Medium	NS	ND
Ethyl propanoate	EE2	NS	ND	NS	ND
Ethyl butanoate	EE4	NS	Low	NS	ND
Ethyl 2-methyl propanoate	EE3	NS	ND	NS	ND
Ethyl hexanoate	EE7	NS	Low	NS	ND
Ethyl heptanoate	EE8	NS	NA	0.22 (0.03)	NA
Ethyl octanoate	EE9	NG	NA	0.22 (0.03)	NA
Ethyl (methylthio) acetate	EE12/TEE2	NS	NA	0.24 (0.02)	NA
S-methyl 2-methylpropanethioate	TE3	NS	NA	0.20 (0.04)	NA
Methyl 2-methylthio acetate	TEE1	NG	NA	0.26 (0.008)	NA
Methyl 3-(methylthio)propionate	TEE3	NG	NA	0.21 (0.008)	NA

Upper part of the table: Metabolic evidence is based on in vitro experiments [13] testing the product specificity of Cm-AAT1-4. The ten metabolites in the upper part of the table were retrieved from the crossing of the 29 ester products tested at [13] with our set of metabolites. Cm-AAT3 (MELO3C024769 and MELO3C024762) and Cm-AAT4 (MELO3C017688) were detected at very low levels at the ripe fruit across the RIL population (Additional file 4) hence correlation values were not computed Median expression values (RPKM) across the RIL population for MELO3C024771 (Cm-AAT1), MELO3C024766 (Cm-AAT2), MELO3C024769 (Cm-AAT3), MELO3C024762 (Cm-AAT3) and MELO3C017688 (Cm-AAT4), respectively: 6777.400, 2881.290, 0.075, 0.840 and 0.000. Lower part of the table: metabolites (out of the 76 metabolites in the data set) with significant (<0.05) positive correlation with CmAAT2. The catalytic ability of CmAAT2 to produce the 6 metabolites was not tested at [13]. In vitro assays not carry at the reference work [13] are marked as NA.
*Full names are as in Table 1.
ζNS – not significant (p value > 0.05); NG – negative correlation; NA - In vitro assays not carry at the reference work [13].
§According to [13]. High production levels: > 1000 mg⁻¹; medium production levels: 100–1000 mg⁻¹; low production levels: < 100 mg⁻¹; ND – not detected.