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Title: Comparative Analysis of Phytohormones and Oxidative Damage in Flag Leaves of Six Contrasting Wheat Genotypes in Response to Drought Stress
Authors: Parisa Sharifi; Reza Amirnia; Eslam Majidi; Hashem Hadi; Foad Moradi; Mozafar Roustaei; Jafar Jafarzadeh
Aff: Department of Agronomy and plant breeding, Faculty of Agriculture, Urmia University, Urmia, Iran
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Keywords: Antioxidants; Drought; Oxidative Stress; Phytohormones; Wheat; Yield.
Abstract:The role of plant hormones and antioxidant systems in water stress tolerance was studied in six contrasting wheat genotypes. Water stress imposed at different stages after anthesis resulted in an increase in hydrogen peroxide content and electrolyte leakage and a decrease in glutathione content in flag leaves of wheat genotypes. The antioxidant enzymes ascorbate peroxidase (APX) and glutathione reductase (GR) also increased significantly under water stress. Tolerant genotypes, which had highest antioxidant protection, had the lowest oxidative damage, while the susceptible genotypes exhibited the lowest antioxidant protection and the highest oxidative damage. Moderately tolerant genotypes showed intermediate behaviour. Exposure to water stress also altered the levels of endogenous hormones in flag leaves of wheat genotypes. Abscisic acid (ABA) content increased in response to water stress in all the genotypes despite different extents. Compared with tolerant genotypes, susceptible genotypes were more responsive to water stress, resulting in larger increases in ABA content. Here, moderately tolerant genotypes also showed intermediate behaviors. The IAA and Gibberellic acid (GA3) contents also decreased during drought stress and the highest their content were observed in tolerant genotypes, followed by moderately tolerant and susceptible genotypes. Our results also showed that the shortened maturity duration and higher thousand kernel weight in tolerant genotypes under water stress is associated to the higher phytohormone content in the flag leaves of these genotypes. It seems that drought tolerance of tolerant genotypes, as represented by higher antioxidant protection and lower oxidative damage, is related to their higher phytohormone contents under water stress