Comparison of lsoflavone concentrations in soybean (Glycine max (L.) merrill) sprouts grown under two different light conditions

We determined and compared the composition and content of isoflavones in the cotyledon, hypocotyl, and root of 17 soybean sprout varieties grown under dark and light conditions. The total average isoflavone concentrations in 17 soybean sprout varieties were 2167 mu g g(-1) (green sprout) and 2538 mu g g(-1) (yellow sprout) in cotyledons, 1169,mu g g-1 (green sprout) and 1132 mu g g(-1) (yellow sprout) in hypocotyls, and 2399 mu g g(-1) (green sprout) and 2852 mu g g(-1) (yellow sprout) in roots. There were no significant differences in total isoflavone concentrations between the green and yellow sprouts. However, significant differences in total isoflavone amounts were observed among the three organs, with roots exhibiting the highest tota I isoflavone concentrations followed by cotyledons and hypocotyls. Total daidzin concentrations of green (775 mu g g(-1)) and yellow (897 mu g g(-1)) sprouts increased to more than 4 times that in seeds (187 mu g g(-1)). Yellow sprouts contained the highest (1122 mu g g(-1)) total genistin concentrations, and green (155 mu g g(-1)) and yellow (155 mu g g(-1)) sprouts had more total glycitin concentrations than seeds. In cotyledons of green and yellow sprouts, genistin, daidzen, and glycitin constituted more than 67%, more than 28%, and less than 4% of the total isoflavone contents, respectively. In hypocotyls, total daidzin represented more than 45% of the total isoflavones, and total glycitin was higher than in cotyledons and roots. Malonylglycoside concentrations were highest in cotyledons, whereas glycoside concentrations were highest in hypocotyls and roots. The high accumulation of isoflavones in roots is consistent with isoflavones serving as signal molecules in the induction of microbial genes involved in soybean (Glycine max) nodulation.