NaCl stress on physio-biochemical metabolism and antioxidant capacity in germinated hulless barley (Hordeum vulgare L.).

BACKGROUND: Hulless barley generally grows in barren fields, where soil salinization is serious. However, only a few studies have been carried out investigating germinated hulless barley under salt stress. In the present study, the effect of NaCl stress on the physio-biochemical metabolism and antioxidant capacity of germinated hulless barley was investigated.

RESULTS: NaCl stress inhibited seedling growth and caused oxidative damage, although it enhanced the accumulation of phenolic compounds and antioxidant capacity. The highest contents of total phenolic and main phenolic acids (vanillic acid, p-coumaric acid, ferulic acid and sinapic acid) were found with 60 mmol L-1 NaCl treatment, whereas 120 mmol L-1 NaCl inhibited the synthesis of phenolic components. Gene expression of phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H), 4-coumarate coenzyme A ligase (4CL), p-coumaric acid 3-hdroxylase (C3H) and caffeic acid/5-hydroxyferulic acid O-methyltransferase (COMT), which participated in the synthesis of phenolic compounds, was up-regulated by NaCl stress, as were the enzyme activities of PAL, C4H and 4CL. NaCl treatment also enhanced the antioxidant enzyme activities of germinated hulless barley.

CONCLUSION: NaCl stress inhibited seedlings growth and caused oxidative damage. Simultaneously, the antioxidant system of germinated hulless barley was enhanced. The results of the present study provide a theoretical basis with respect to the growth of hulless barley under salt stress. © 2018 Society of Chemical Industry.