Upregulation of Isoflavonoids and Soluble Proteins in Edible Legumes by Light and Fungal Elicitor Treatments

Abstract

Objective: In this study, our working hypothesis was that continuous light and fungal elicitation treatment of legume seedlings would lead to enhanced levels of isoflavonoids and soluble proteins. Results: Based on short-term light and dark treatments, isoflavonoid (genistein, genistin, daidzein, and daidzin) and soluble protein concentrations were significantly upregulated in the "light" environment compared to the "dark" environment for all edible legume species (kudzu vine, soybean, garbanzo bean, fava bean, mung bean, adzuki bean) that were tested. Kudzu seedlings showed the highest levels of both isoflavonoids and soluble proteins after light-elicited upregulation compared to the other legumes analyzed. All legumes showed less up-regulation of isoflavonoid synthesis when treated with Phytophtora sojae fungal elicitor. Oligosaccharide fungal elicitor caused no such upregulation. Conclusions: The findings in this study show that edible legume seedlings have enhanced levels of isoflavonoids and soluble proteins when they are grown in the light compared to the conventional practice of growing such seedlings in the dark. This will clearly result in significant improvement in their nutritive and medicinal value.