Department Of Botany

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Understanding cross-tolerance mechanism and effect of drought priming on individual heat stress and combinatorial heat and drought stress in chickpea
(Springer, 2022-03-15T00:00:00) Yadav, Renu; Juneja, Sumandeep; Kumar, Rashpal; Saini, Rashmi; Kumar, Sanjeev
In northern India, chickpea experiences abrupt heat and drought stress during the late developmental stage and entails significant production loss. In the present study, the effect of heat stress and combined stress (heat and drought) was assessed in five varieties of chickpea along with the underlying mechanism of cross-tolerance by priming. Healthy seedlings (24�days old) were primed with mild drought stress and exposed to three different temperatures, i.e., 38��C, 35��C, and 32��C for 12, 24, and 36�h respectively, and also in combination with drought. The damage and tolerance were evaluated based on biochemical and physiological indicators. Results indicate that significant response was observed at 35��C as compared to 32 and 38��C in terms of decrease in leaf water content, increased electrolyte leakage and lipid peroxidation, decreased chlorophyll content, increased accumulation of proline and total sugars, and increased antioxidative activity of superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase, and glutathione reductase. The consequence of combined stress was more distinct than the individual heat stress and cannot be extrapolated from the synergistic effect of the two stresses. In addition, priming induced cross-tolerance at 35��C by improving the membrane damage, photorespiration, photosynthetic pigment, osmolyte accumulation, and some antioxidative enzymes. On the basis of all the above parameters, PDG4 was identified as the best performing variety and tolerant to heat stress while GPF2 was the worst performing and sensitive to heat stress. It can be inferred that both severity and duration of stress are important and priming can be considered as an important tool to induce cross-tolerance in crop plants. � 2022, The Author(s), under exclusive licence to Korean Society of Crop Science (KSCS).
Understanding cross-tolerance mechanism and effect of drought priming on individual heat stress and combinatorial heat and drought stress in chickpea
(Springer, 2022-03-15T00:00:00) Yadav, Renu; Juneja, Sumandeep; Kumar, Rashpal; Saini, Rashmi; Kumar, Sanjeev
In northern India, chickpea experiences abrupt heat and drought stress during the late developmental stage and entails significant production loss. In the present study, the effect of heat stress and combined stress (heat and drought) was assessed in five varieties of chickpea along with the underlying mechanism of cross-tolerance by priming. Healthy seedlings (24�days old) were primed with mild drought stress and exposed to three different temperatures, i.e., 38��C, 35��C, and 32��C for 12, 24, and 36�h respectively, and also in combination with drought. The damage and tolerance were evaluated based on biochemical and physiological indicators. Results indicate that significant response was observed at 35��C as compared to 32 and 38��C in terms of decrease in leaf water content, increased electrolyte leakage and lipid peroxidation, decreased chlorophyll content, increased accumulation of proline and total sugars, and increased antioxidative activity of superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase, and glutathione reductase. The consequence of combined stress was more distinct than the individual heat stress and cannot be extrapolated from the synergistic effect of the two stresses. In addition, priming induced cross-tolerance at 35��C by improving the membrane damage, photorespiration, photosynthetic pigment, osmolyte accumulation, and some antioxidative enzymes. On the basis of all the above parameters, PDG4 was identified as the best performing variety and tolerant to heat stress while GPF2 was the worst performing and sensitive to heat stress. It can be inferred that both severity and duration of stress are important and priming can be considered as an important tool to induce cross-tolerance in crop plants. � 2022, The Author(s), under exclusive licence to Korean Society of Crop Science (KSCS).
Preconditioning of chickpea seedlings for terminal heat stress: understanding associated mechanism and HSP's expression
(Central University of Punjab, 2014) Yadav, Renu; Kumar, Sanjeev
Chickpea (Cicer arietinium L.) is the second most important pulse crop grown worldwide. Changes in the cropping system, competition from other cash crops (wheat) and global warming are pushing chickpea to relatively warmer growing environment. In northern part of country chickpea come across with terminal high temperature stress during reproductive stage which lead to reduced grain yield. Therefore to prevent the plant from incoming heat stress, 11 day chickpea seedling were preconditioned with mild drought stress, then put on recovery for six days and then recovered seedlings were exposed to lethal stress (where temperature was increased step wise from 30?C to 36?C). This study revealed that % EL, Lipid peroxidation increased with the increase in temperature while percent TTC reduction and total protein content decreased with the increase in temperature. Antioxidative enzymes provide the major defence against the ROS generated during the abiotic stress, and it was found that activity of SOD, CAT and APX enzyme increased proportionately with the rising temperature. HSP's act as molecular chaperons and are over expressed at both mRNA and protein level in preconditioned seedlings exposed to high temperature stress as compared to non- preconditioned ones. To conclude the whole study, results obtained clearly reveal that preconditioning with drought stress has the ability to improve tolerance above ambient temperature (27?C 7?C), thereafter preconditioning did not have any influence in terms of the improvement in membrane damage and level of antioxidants. Higher expression of sHSP's is corroborated with the low expression of antioxidants.

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