Heat acelimation and chemical pre-treatments induccd thermotolerancc in chickpea

Abstract

Induced heat-tolerance triggered by heat acclimation treatment and foliar application of salicylic acid and abscisic acid were evaluated in three different genotypes of chickpea (Cicer arietinum L.) distinctly differing in their sensitivity to heat stress. Seedlings pre-treated with 100uM salicylic acid (SA) and 50 uM abscisic acid (ABA) showed improved heat tolerance to a lethal temperature of 46°C than the untreated control seedlings. Heat stress increased lipid peroxidation of membranes and reduced plant survival. Protein and proline contents increased significantly in pre-treated seedlings. Cell membrane stability also increased remarkably in pre-treated seedlings of all three genotypes. Changes in activities of antioxidative enzymes like peroxidase, ascorbate peroxidase in pre-treated seedlings revealed increase in enzymatic activities which declined sharply at lethal temperuturc. Quantum of increase in enzymatic activity was however higher in thermotolerant genotype in comparison to heat susceptible genotype. Thermotolerant genotype also exhibited constitutively higher antioxidative activities. Catalase activity, in contrast, showed a significant decrease in its activity in pre-treated seedlings following exposure to lethal temperature. These results indicate that heat acclimation treatment and application of SA and ABA show great potential in inducing heat tolerance in chickpea seedlings and these can be further analyzed to understand their role in thermoprotection.