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Figure 1. Anthocyanin metabolic pathway in Glycine max. Enzyme abbreviations and the flower and seed coat color loci (in uppercase letters) show the three branches leading to the synthesis of the purple delphinidins, pink pelargonidins, red cyanidins, and the flavonols. The flavonol kaempferol derived from dihydrokaempferol was not included to simplify the scheme. Wp, W3, and Wm are the flower color markers associated with the indicated enzymes in the pathway based on molecular and genetic evidence (Zabala and Vodkin, 2005; Fasoula et al., 1995; Takahashi et al., 2007). The suggested W1 assignment (marked by a circle) as F3'5'H was made by Buzzell et al. (1987) based on biochemical evidence. The I and T are the well-characterized loci that control seed pigmentation and that encode CHS (Todd and Vodkin, 1996) and F3'H (Toda et al., 2002; Zabala and Vodkin, 2003), respectively. PAL, phenylalanine ammonia-lyase; C4H, cinnamate 4-hydroxylase; 4CL, 4-coumarate: CoA ligase; CHS, chalcone synthase; CHI, chalcone isomerase; F3'H, flavonoid 3'-hydroxylase; F3'5'H, flavonoid 3'5'-hydroxylase; F3H, flavanone 3-hydroxylase; DFR, dihydroflavonol-4-reductase; ANS, anthocyanidin synthase (also called LDOX, leucoanthocyanidin dioxygenase); UFGT, UDP-flavonoid glucosyltransferase; FLS, flavonol synthase.
