Identification and Functional Characterization of UDP-Glycosyltransferases Involved in Isoflavone Biosynthesis in Astragalus membranaceus .

Isoflavones are rich natural compounds present in legumes and are essential for plant growth and development. Moreover, they are beneficial for animals and humans. Isoflavones are primarily found as glycoconjugates, including calycosin-7---d-glucoside (CG) in , a legume. However, the glycosylation mechanism of isoflavones in remains unclear. In the present study, three uridine diphosphate (UDP)-glycosyltransferases (UGTs) that may be involved in the biosynthesis of isoflavone were identified in the transcriptome of . Enzymatic analysis revealed that AmUGT88E29 and AmUGT88E30 had high catalytic activity toward isoflavones . In addition, AmUGT88E29 and AmUGT88E30 could accept various flavones, flavanones, flavonols, dihydroflavonols, and dihydrochalcones as substrates. AmUGT71G10 was only active against phloretin and dihydroresveratrol. Overexpression of significantly increased the contents of CG, an isoflavone glucoside, in the hairy roots of . This study provided candidate genes for the potential metabolic engineering of flavonoid compounds in plants and a valuable resource for studying the calycosin glycosides biosynthesis pathway.