Root-zone addition of glutathione and putrescine synergistically regulate GSH–NO metabolism to alleviate Cr (VI) toxicity in rapeseed seedlings

Abstract

Abstract Glutathione (GSH) and nitric oxide (NO) regulate several physiological processes in plants under normal and stress conditions. We investigated the individual versus the interactive effect of exogenously applied GSH and PUT in rapeseed seedlings under short-term and long-term hexavalent chromium (Cr + 6 ) stress during separate experiments. Results revealed that both these metabolites reduced Cr + 6 toxicity in diverse canola cultivars. The Cr6＋ stress reduced root and shoot biomass while an increase in carotenoids was evident due to short-term stress exposure. The long-term exposure caused a prominent decrease in Chl a and total Chl (even short-term stress caused a reduction in cv. Rainbow) while, an increase in the carotenoids. Leaf endogenous GSH levels increased in all cultivars after 07-days Cr6＋ exposure and this trend was consistent with increased leaf SOD activities. The co-application of PUT and GSH via root medium alleviated the inhibitory effects of Cr + 6 . Furthermore, increased GSH and nitric oxide (NO) fraction in specific plant parts represented cross-talk between these two metabolites under Cr-stress. Above all, improvement in antioxidant capacity and ROS-scavenging, at least in some parts successfully resulted in GSH and PUT-mediated mitigation of Cr + 6 toxicity.