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

In the present study, the role of hydrogen sulfide (HS) 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 HS (donor sodium hydrogen sulphide (NaHS; 40 μM)) under stress, HS 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 F/F, F/F, φE, ѱ PI except F/F and enhancement in energy flux parameters such as ABS/RC, TR/RC, ET/RC and DI/RC was obtained. Exogenous HS 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 HS (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 HS was also justified using the scavenger of HS (HT; 200 μM) and inhibitor of enzymes of HS (PAG; 100 μM). Thus, present study emphasizes the role of NaHS as HS 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.