Insights into changes of enzyme activity for maintaining redox homeostasis in chickpea under water deficit stress

Receding residual soil moisture due to depleting water table coupled with increasing temperature at the end of the crop season invokes a water deficit stress condition that affects chickpea productivity. Germination is the most important phase responsible for crop establishment. In the present study, biochemical mechanism underlying water deficit stress tolerance behaviour has been compared in two contrasting chickpea cultivars during seedling growth. Effect of water deficit stress on antioxidative enzymes and their electropherogram, non-enzymatic antioxidants, proline metabolism enzymes in cotyledons, roots and shoots; 2D electrophoretic analysis in shoots of (ICC4958), water deficit-tolerant (ICC4958) and -susceptible (ILC3279) chickpea cultivars were investigated. Sustained activities of superoxide dismutase (SOD), peroxidase (POD) and proline metabolism enzymes ∆1-pyrolline-carboxylate synthetase (PCS) and proline dehydrogenase (PDH), along with the induced expression of APX-2 and GR-3 isoforms in cotyledons of ICC4958 under water stress, helped to combat oxidative stress as compared to cotyledons of ILC3279 in which the corresponding enzymatic activities and isozyme expressions were decreased. Selective induction and maintained enzymatic activities in ICC4958 such as increased SOD and maintained APX activity in roots, lower decline in GR in shoots, induced expression of GR-1 and APX-2 in roots and SOD-1 in shoots along with increased proline content in shoots and increased hydroxyl radical scavenging activity in roots and shoots help to mediate stress tolerance as compared to ILC3279. 2D electrophoretic profile of shoots of both the cultivars revealed that stress reduced the expression of protein.