Hydrogen sulfide implications on easing NaCl induced toxicity in eggplant and tomato seedlings.

In the present study, the role of hydrogen sulfide (H2S) in alleviating NaCl (20 mM) induced toxicity on growth, photosynthetic pigments and photochemistry of PS II, and impact on oxidative stress and antioxidant systems of eggplant and tomato was studied. To confirm the role of H2S (donor sodium hydrogen sulphide (NaHS; 40 µM)) under stress, H2S scavenger; hypotaurine (HT; 200 µM) and inhibitor, propargylglycine (PAG; 100 µM) in combination with NaHS was added to the growth medium of NaCl stressed seedlings. The NaCl reduced the overall growth of the seedlings as the Na+ uptake was increased which led to removal of K+, thereby Na+/K+ homeostasis was disturbed. This condition caused severe impact on photosynthetic pigments and PS II photochemistry, thus significant decline in the values of fluorescence kinetics parameters such as Fv/Fm, FV/F0, φE0, ѱ0, PIABS except F0/FV and enhancement in energy flux parameters such as ABS/RC, TR0/RC, ET0/RC and DI0/RC was obtained. Exogenous H2S not only abolished the toxic symptoms in test seedlings but also completely alleviated the decline in growth in case of tomato seedlings. Reactive oxygen species accumulation was significantly declined in both the seedlings as evident by in vitro and in vivo analysis with the supplementation of NaHS, indicating appreciable recovery in membrane damage caused by NaCl toxicity. Antioxidative enzymes: SOD, POD, CAT and GST activities were further stimulated in response to H2S (NaHS) supplementation to the stressed seedlings, thus maintaining the redox homeostasis of cell and bringing the seedlings back to the healthy state. Moreover, the role of endogenous and exogenous H2S was also justified using the scavenger of H2S (HT; 200 µM) and inhibitor of enzymes of H2S (PAG; 100 µM). Thus, present study emphasizes the role of NaHS as H2S donor in alleviating NaCl stress in crops particularly vegetables tomato and eggplant, and may be considered as a part of important strategies to cope up with NaCl toxicity which is prevailing in natural field condition.