Correlation of saponarin content with biosynthesis-related gene expression in hulled and hulless barley (Hordeum vulgare L.) cultivars

Saponarin found in young barley sprouts has a variety of beneficial biological and pharmacological properties, including antioxidant, hypoglycemic, antimicrobial, and hepatoprotective activities. Our previous work demonstrated that saponarin content was correlated with the expression levels of three biosynthetic pathway genes [chalcone synthase (HvCHS1), chalcone isomerase (HvCHI), and UDP-Glc:isovitexin 7-O-glucosyltransferase (HvOGT1)] in young barley seedlings under various abiotic stress conditions. In this study, we investigated the saponarin content and expression levels of three saponarin biosynthetic pathway genes in hulled and hulless domestic barley cultivars. In the early developmental stages, some hulled barley cultivars (Kunalbori1 and Heukdahyang) had much higher saponarin contents than did the hulless barley cultivars. An RNA expression analysis showed that in most barley cultivars, decreased saponarin content correlated with reduced expression of HvCHS1 and HvCHI, but not HvOGT1. Heat map analysis revealed both specific increases in HvCHS1 expression in certain hulled and hulless barley cultivars, as well as general changes that occurred during the different developmental stages of each barley cultivar. In summary, our results provide a molecular genetic basis for the metabolic engineering of barley plants to enhance their saponarin content.