Cross-priming accentuates key biochemical and molecular indicators of defense and improves cold tolerance in chickpea (Cicer arietinum L.)

摘要

Cold environment favors long vegetative phase but also impose substantial loss by damaging reproductive functioning in chickpea. Field temperature below 10 degrees C is even more detrimental for reproductive development, enhances floral and pod abortion. In this study, contrasting chickpea varieties PDG3 and GPF2 were exposed to drought, recovered, and subsequently exposed to lethal cold stress similar to 4-5 degrees C with an aim to induce defense response against cold shock. Physiological, biochemical, and molecular signatures related to damage and defense, i.e., membrane damage, antioxidative enzymes, fatty acid desaturase (CaFAD2.1), and small HSPs (CaHSP18.5 and CaHSP22.7), were analyzed. Drought pretreatment/preconditioning maintained the membrane stability in the cold by managing malondialdehyde (MDA) content and lipoxygenase (LOX) activity. Improved mitochondrial functioning (TTC reduction), increased activity of catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) proved better cellular functioning during cold exposure. The expression and activity of superoxide dismutase (CaSOD) were down-regulated in both varieties, but CaCAT, CaAPX, CaGR, and CaFAD2.1 expressions were up-regulated in GPF2. Small heat shock protein CaHSP22.7 was also up-regulated in drought preconditioned PDG3 and GPF2 and after cold shock. Drought pretreatment/preconditioning significantly improved membrane damage during cold exposure, induced antioxidative system, and up-regulated FAD2. This study also pointed the possible role of CaHSP22.7 in cold tolerance and CaHSP18.5 in drought stress. The sensitive variety (GPF2) was positively responsive to preconditioning as this variety showed improvement in defense-related parameters; however, genotypic variations were observed in PDG3.