Analysis of flavonoids in flower petals of soybean near-isogenic lines for flower and pubescence color genes

W1, W3, W4, and Wm genes control flower color, whereas T and Td genes control pubescence color in soybean. W1, W3, Wm, and Tare presumed to encode flavonoid 3'5'-hydroxylase (EC 1.14.13.88), dihydroflavonol 4-reductase (EC 1.1.1.219), flavonol synthase (EC 1.14.11.23), and flavonoid 3'-hydroxylase (EC 1.14.13.21), respectively. The objective of this study was to determine the structure of the primary anthocyanin, flavonol, and clihydroflavonol in flower petals. Primary component of anthocyanin in purple flower cultivars Clark (W1W1 w3w3 W1W1 WmWm TT TdTd) and Hato soy (W1W1 w3w3 W1W1 WmWm tt TdTd) was malvidin 3,5-di-O-glucoside with delphiniclin 3,5-di-O-glucoside as a minor compound. Primary flavonol and dihydroflavonol were kaempferol 3-O-gentiobioside and aromadendrin 3- O-glucoside, respectively. Quantitative analysis of near-isogenic lines (NILs) for flower or pubescence color genes, Clark-w1 (white flower), Clark-w4 (near-white flower), Clark-W3w4 (dilute purple flower), Clark-t (gray pubescence), Clark-td (near-gray pubescence), Harosoy-wm (magenta flower), and Harosoy-T(tawny pubescence) was carried out. No anthocyanins were detected in Clark-w1 and Clark-w4, whereas a trace amount was detected in Clark-W3w4. Amount of flavonols and dihydroflavonol in NILs with w1 or w4 were largely similar to the NILs with purple flower suggesting that W1 and W1 affect only anthocyanin biosynthesis. Amount of flavonol glycosides was substantially reduced and clihydroflavonol was increased in Harosoy-wm suggesting that Wm is responsible for the production of flavonol from clihydroflavonol. The recessive mim allele reduces flavonol amount and inhibits co-pigmentation between anthocyanins and flavonols resulting in less bluer (magenta) flower color. Pubescence color genes, Tor Td, had no apparent effect on flavonoid biosynthesis in flower petals.