Yeast extract elicited isoflavonoid accumulation and biosynthetic gene expression in Pueraria candollei var. mirifica cell cultures

Yeast extract (YE) has emerged as a potent biotic elicitor that can induce plant defense responses, leading to enhanced phytoalexin accumulation. Increased production of two isoflavones—daidzein and genistein—that are widely used in pharmaceutical industries was elicited using YE in suspension cell cultures of Pueraria candollei var. mirifica. Compared with the controls, cells treated with 2 mg/L YE for 21 days produced 11-fold increased amounts of daidzein and genistein in the suspension cultures (5.12 and 0.34 mg/g dry weight (DW), respectively). Furthermore, YE treatment significantly upregulated isoflavonoid biosynthesis, as revealed via gene expression studies. In particular, among genes involved in daidzein and genistein biosynthesis, the isoflavone synthase and isoflavone reductase genes were significantly upregulated and the chalcone isomerase and 2,7,4′-trihydroxyisoflavanone dehydratase genes were significantly downregulated; moreover, these changes were associated with the accumulation of these two isoflavones in suspension cell cultures. Overall, the results obtained in this study both emphasize the utility of YE for enhancing the in vitro production of the two bioactive isoflavones examined for pharmaceutical and nutraceutical utilization and advance our understanding of their biosynthesis in response to YE elicitation.