High Salinity Induced Alternations of Protein Profile and Antioxidant Activity in Rice (Oryza sativa L.)

Indicator of oxidative stress such as H₂O₂ content was elevated steadily in shoot tissues of rice seedlings with the linear increment of salinity concentrations, the increase was significant in both control and salt-stressed seedlings. Interestingly, the oxidants were increased slightly in desalinized seedlings (400mM NaCl experienced seedlings transferred to 0mM NaCl concentration). Twenty-one days old seedlings of rice (Oryza sativa L.) treated with different concentrations of NaCl (100, 200, and 400mM) under hydroponic culture. A significant amount of total soluble proteins were drawn out from different seedlings after 7d of treatment and partially characterized by SDS-PAGE. The comparative protein profile analyzed on SDS-PAGE indicated an apparent Salt- Sensitive Protein (SSP)-23-kDa protein which was decreased with proportionally increased NaCl concentrations whereas reappeared in desalinized condition. The antioxidant enzymes viz. SOD and APX were significantly higher in shoot tissues of salt-stressed as compared to the control seedlings. Salt-stressed also induces the high content of GSSG significantly in seedlings. The nonenzymatic antioxidant molecules such as reduced GSH content were decreased in salt-stressed seedlings as compared to control, interestingly it was decreased again in desalinized seedlings. This suggests that all oxidants, enzymatic antioxidants, and antioxidants were changed in cellular level collinearly with perturbation of protein profile in both salinized and desalinized shoot tissues of seedlings.