Browsing by Author "Nayyar H."

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    Alternate mild drought stress (−0.1 MPa PEG) immunizes sensitive chickpea cultivar against lethal chilling by accentuating the defense mechanisms
    (Polish Academy of Sciences, 2016) Kaur S.; Jairath A.; Singh I.; Nayyar H.; Kumar S.
    The changes in climate particularly, the rise in temperature and humidity affect the physiological functions of plants subsequently affecting crop productivity adversely. A strategy is required which can be directly implemented in fields to induce the tolerance in crop plants. In present study, two chickpea varieties with contrasting sensitivity PDG3 (Tolerant) and GPF2 (Sensitive) were raised hydroponically, preconditioned with mild drought stress (0.1 MPa PEG-6000) for 3 days (above 0.1 MPa is lethal) and subsequently recovered for double time (6 days) and finally exposed to lethal cold stress (4 °C) for 3 days. We hypothesize that preconditioning with non-lethal drought stress may immunize the plants to combat lethal cold stress. Membrane integrity improved in root and shoot, lipid peroxidation decreased to control level in preconditioned seedlings. Cellular respiration ability (% TTC reduction) increased in the preconditioned seedlings to almost 90 % in the shoot and 60 % in the root, concurrently it was 45 % in non-preconditioned seedlings. Proline content also increased in preconditioned seedlings, especially roots. Carbohydrate had a shift in terms of a high amount of total, reducing sugars and starch in non-preconditioned seedlings compared to preconditioned. Both PDG3 and GPF2 showed enhanced SOD, CAT and GPOX activity indicating tolerance against cold-induced oxidative stress and preconditioning induced improvement against lethal cold stress.
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    Cross-priming accentuates key biochemical and molecular indicators of defense and improves cold tolerance in chickpea (Cicer arietinum L.)
    (Polish Academy of Sciences, Institute of Slavic Studies, 2019) Saini R.; Adhikary A.; Nayyar H.; Kumar S.
    Cold environment favors long vegetative phase but also impose substantial loss by damaging reproductive functioning in chickpea. Field temperature below 10��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 ~ 4�5��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. � 2019, Franciszek G�rski Institute of Plant Physiology, Polish Academy of Sciences, Krak�w.