Expression Analysis of Flavonoid-related Genes in Green and White Asparagus Spears

We performed an expression analysis of flavonoid-related genes such as chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3′H), flavonoid 3´-hydroxylase (F3′H), and flavonol synthase (FLS) in order to investigate the effects of light exposure on rutin biosynthesis and to determine the rutin content in green and white asparagus spears (Asparagus officinalis). Gene expression levels for the downstream enzymes in the biosynthesis pathway, i.e., F3′H and FLS, were significantly higher in green spears than in white spears; however, no significant difference was observed in the expression of upstream genes, such as CHS, CHI, and F3H. Furthermore, the expression of FLS was the lowest among all flavonoid-related genes, which indicates that it might play an important role in rutin regulation. Rutin remained undetected in white asparagus spears, while green asparagus had relatively high amounts present. The results of this study may explain the molecular basis of the relationship between light exposure and rutin biosynthesis in asparagus spears.