Trehalose mitigates sodium chloride toxicity by improving ion homeostasis, membrane stability, and antioxidant defense system in Indian mustard

Salt stress, particularly sodium chloride (NaCl), poses a significant threat to agricultural sustainability by limiting crop growth and development. The present study aimed to examine the effect of leaf-applied trehalose (Tre) on ion homeostasis, photosynthesis, antioxidant defense mechanisms, osmolyte accumulation, cell viability, oxidative stress biomarkers, and histo-microscopical analyses in Indian mustard under NaCl stress. Sodium chloride stress drastically decreased growth, water status, protein content and net photosynthetic rate, while increasing lipid peroxidation, ion toxicity, cell death, and electrolyte leakage due to the excessive accumulation of reactive oxygen species (ROS) in Indian mustard. Foliar fertigation of Tre significantly increased growth traits, nutrient acquisition, chlorophyll content, osmolyte accumulation, protein content, antioxidant enzyme activities, stomatal aperture, and cell viability, while considerably reducing leaf Na+ content and NaCl-generated ROS toxicity in Indian mustard. The Tre application enhanced shoot dry weight by 16 %, net photosynthetic rate by 19.37 %, superoxide dismutase activity by 10 %, nitrogen content by 13.32 %, seed yield by 23 % and oil yield by 27 %, while decreased superoxide anion content by 26 %, sodium ion content by 14.47 % and malondialdehyde content by 11.41 % over 0 mM NaCl treatment. Moreover, the trehalose-mediated reduction in ROS production was further validated with histochemical and microscopical localization analyses. Our data support the notion that Tre supplementation improves NaCl stress tolerance in Indian mustard by mitigating the detrimental impacts of ionic and oxidative stress. This finding suggests that Tre could serve as an alternative biotechnological tool in other types of crops.