Physiological and biochemical evaluation for acquired thermotolerance in pigeonpea (Cajanus cajan L. Millsp.) at seedling stage
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was conducted to study the physiological and biochemical evaluation for acquired thermotolerance in three pigeonpea (Cajanus cajan L. Millsp.) genotypes at seedling stage. Heat acclimation (45°C for 3h) and salicylic acid (0.5 mM and 1 mM for 3h) pre-treatments induced physiological changes in terms of seedling length, seedling weight, RGR, electrolyte leakage and RWC and biochemical changes in terms of cellular respiration, total soluble sugars, proline content, photosynthetic efficiency, MDA and H2O2 content and changes in antioxidant enzyme activities (CAT and POX) imparting thermotolerance. These pre-treatments conferred protection against heat stress through improved seedling growth, reduced electrolyte leakage, increased RWC, increased accumulation of sugars and proline, improved photosynthetic efficiency, reduced MDA and H2O2 content. Antioxidant defense system was induced in terms of CAT (average 1.02 fold increase in heat acclimated, 0.77 fold in 0.5 mM SA and 1 fold in 1 mM SA) and POX (average 1.30 fold increase in heat acclimated, 1.24 fold in 0.5 mM SA and 1.37 fold in 1 mM SA) activity in all genotypes. Separation of proteins through SDS-PAGE revealed the accumulation of some new proteins (heat shock proteins) of low and high molecular weight in heat acclimated seedlings to overcome the harmful effects of heat stress. Among the three genotypes, AL 1931 performed best and acquired maximum thermotolerance. Although both the pre-treatments resulted in induction of thermotolerance but SA pre-treatment proved better in the present study.
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