Exogenous application of salicylic acid enhanced the rutin accumulation and influenced the expression patterns of rutin biosynthesis related genes in Fagopyrum tartaricum Gaertn leaves

Except for buckwheat, no cereal or pseudocereal contains any detectable rutin. This study was carried out to compare the rutin content in leaves treated with various concentrations of salicylic acid (SA) (50?mg?l^?1, 100?mg?l^?1, 150?mg?l^?1) for various lengths of time (2?C120?h) to those of untreated F. tartaricum. Rutin content in leaves during the early stages of SA treatment (100?mg?l^?1, 150?mg?l^?1; 24?C48?h) were higher than at other times. The highest rutin content (40.3?mg?gFW^?1) was found in leaves treated with 150?mg?l^?1 SA for 48?h. We cloned partial cDNAs of five genes known to be related to rutin biosynthesis from the leaves of F. tataricum using RACE. These genes were chalcone synthase (FtCHS), flavonol synthase (FtFLS-like), flavone 3-hydroxylase (FtF3H), 4-coumaroyl CoA ligase (Ft4CL), and 4-coumaroyl CoA ligase 2 (Ft4CL2). The protein sequences of these genes were analyzed by similarity searching and phylogenetic trees. Apart from the FtFLS-like gene, which had poor identity with F. esculentum, the other genes showed high similarity to those in F. esculentum. During the early stages of SA treatment (24?C48?h), expression levels of four genes (FtCHS, FtFLS-like, FtF3H, and Ft4CL) were higher than controls but that of Ft4CL2 was not. Most notably, the expression level of FtFLS-like 24?h after application of 150?mg?l^?1 SA was 14.79 times of the control. These results suggest that rutin content can be enhanced to great extent by SA treatment and the gene expression patterns of rutin-biosynthesis-related genes are regulated by SA.