Exogenous trehalose ameliorates methyl viologen induced oxidative stress through regulation of stomatal pore opening and glutathione metabolism in tomato seedlings

Abstract

Oxidative burst is the common thread linking all abiotic and biotic stressors. So in this study non-reducing disaccharide trehalose (Tre) has been examined for attenuation of oxidative stress, imposed through methyl viologen (MV) foliar spray in tomato seedlings. Initially the ameliorating property was ascertained by leaf disc senescence and stomatal pore opening assay, before carrying out the foliar spray on seedlings. Both these assays showed Tre mediated mitigation of MV induced oxidative stress. It was also observed that trehalose dose determines the extent of stomatal pore opening. MV treated seedlings showed more reactive oxygen species (ROS) accumulation compared to control, Tre and MV + Tre treated plants both histochemically and quantitatively. Damage due to ROS accumulation was documented by quantifying malondialdehye and lipoxygenase activity. Finally, the response of the tomato seedlings to oxidative stress was monitored by quantifying the antioxidant enzyme activities and non-enzymatic antioxidant content under stressed and unstressed conditions. Also transcript levels of glutathione synthetase (GS) and gamma-glutamylcysteine synthetase (γ-ECS), enzymes responsible for GSH synthesis; and transcription factors no apical meristem ATAF and cup-shaped cotyledon (NAC2) and dehydration-responsive element-binding (DREB) were found to increase on application of Tre. All of these experimentations showed better adaptability and survivability of the seedlings treated exogenously with both MV and Tre in comparison to those treated only with MV.