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. 2013 Oct 25;201(2):466–475. doi: 10.1111/nph.12558

Figure 1.

Figure 1

Flavonoid biosynthesis pathway in Arabidopsis thaliana. (a) Scheme of flavonoid biosynthesis. CHS (TT4), chalcone synthase; F3′H (TT7), flavonoid 3′-hydroxylase; DFR (TT3), dihydroflavonol 4-reductase; FLS, flavonol synthase; ANS (TT18), anthocyanidin synthase; UGT78D1, flavonol 3-O-rhamnosyltransferase; UGT78D2, flavonoid 3-O-glucosyltransferase; UGT89C1, flavonol 7-O-rhamnosyltransferase. As shown by Yin et al. (2012), the combined loss of UGT78D1 and UGT78D2 does not imply an accumulation of flavonol aglycones because of a feedback inhibition of flavonol biosynthesis. (b) Glycosylation reactions catalyzed by UGT78D1, UGT78D2 and UGT89C1 (Jones et al., 2003; Tohge et al., 2005; Yonekura-Sakakibara et al., 2007). Abbreviations: Kaempferol (k); rhamnoside (rha); glucoside (glu). k1, k-3-O-rha-7-O-rha; k2, k-3-O-glu-7-O-rha; k3, k-3-O-[rha (1->2 glu)]-7-O-rha; q1, q2 and q3 are quercetins structurally equivalent to k1, k2 and k3, respectively.