UV-B treatment enhances phenolic acids accumulation and antioxidant capacity of barley seedlings

The effects of ultraviolet B (UV-B, 280–315 nm) on phenolic acids content, key enzymes activity and antioxidant capacity as well as the related gene expressions of barley seedlings were investigated in the present study. Results showed that UV-B treatment increased phenolics content including vanillic acid, p-coumaric acid, ferulic acid and erucic acid in barley seedlings, significantly. The mRNA levels and activities of phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H), 4-coumarate coenzyme A ligase (4CL), p-coumaric acid 3-hdroxylase (C3H), caffeic acid O-methyltransferase (COMT) and ferulic acid 5-hydroxylase (F5H) involved in phenolic acid synthesis increased under UV-B treatment as well. In addition, UV-B radiation enhanced the antioxidant enzymes activity and the gene expressions of barley seedlings, including superoxide dismutase (SOD), peroxidase (POD) and glutathione reductase (GR), and improved 2,2-diazo-bis (3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt (ABTS) and 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) free radical scavenging ability. In conclusion, UV-B treatment led to the upper-regulation of related enzymes activity and gene expression, resulting in the accumulation of phenolic acids in barley seedlings, thus contributing to the enhancement of antioxidant system. •UV-B treatment accumulated phenolic acids of barley seedlings.•UV-B treatment regulating the mRNA levels and activities in phenolic acid synthesis.•UV-B treatment contributed to the enhancement of antioxidant system.•UV-B receptor UVR8 might involve in mediating the accumulation of phenolic acids.