Exogenous salicylic acid improves photosynthesisand growth through increase in ascorbate-glutathione metabolism and S assimilationin mustard under salt stress

摘要

Ascorbate (AsA)–glutathione (GSH) cycle metabolism has been regarded as the most important defense mechanismfor the resistance of plants under stress. In this study the influence of salicylic acid (SA) was studied on ascorbate-glutathione pathway, S-assimilation, photosynthesis and growth of mustard (Brassica junceaL.) plants subjected to100 mM NaCl. Treatment of SA (0.5 mM) alleviated the negative effects of salt stress and improved photosynthesis andgrowth through increase in enzymes of ascorbate-glutathione pathway which suggest that SA may participate in theredox balance under salt stress. The increase in leaf sulfur content through higher activity of ATP sulfurylase (ATPS) andserine acetyl transferase (SAT) by SA application was associated with the increased accumulation of glutathione (GSH)and lower levels of oxidative stress. These effects of SA were substantiated by thefindings that application of SA-analog, 2,6, dichloro-isonicotinic acid (INA) and 1 mM GSH treatment produced similar results on rubisco,photosynthesis and growth of plants establishing that SA application alleviates the salt-induced decrease inphotosynthesis mainly through inducing the enzyme activity of ascorbate-glutathione pathway and increased GSHproduction. Thus, SA/GSH could be a promising tool for alleviation of salt stress in mustard plants.