Antioxidative response in different sorghum species under short-term salinity stress

Seedlings of sorghum varieties (M35-1, a drought tolerant species; SPV-839, a drought sensitive one) differing in their drought tolerance were subjected to 150 mM NaCl stress for a short duration of time (up to 72 h). Both the varieties failed to exhibit efficient ion exclusion mechanism like that of salt tolerant species, but in turn resulted in higher accumulation of Na⁺ and Cl⁻ ions over a period of 72 h salt stress. In addition, accumulation of calcium, potassium and proline in seedlings of sorghum varieties was moderate to short-term NaCl stress. The modulation of antioxidant components significantly diverged between the two varieties during seed germination, further the efficiency of antioxidant scavenging system is maintained during short-term NaCl treatments. In comparison to tolerant variety, the sensitive variety depicted higher SOD activity under control and salinity treatments but specific activity of catalase was significantly reduced. In contrast, drought tolerant variety exhibited efficient hydrogen peroxide scavenging mechanisms with higher catalase and GST activities under control and salt stress conditions, but not in the sensitive one. In conclusion, our comparative studies indicate that drought tolerant and susceptible varieties of sorghum induce efficient differential oxidative components of enzymatic machinery for scavenging ROS thereby alleviating the oxidative stress generated by salt stress during seedling growth.