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چکیده
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The aim of the present study was to investigate the physiological mechanism of γ-aminobutyric acid (GABA) and penconazole (PEN) and their relationship with salt tolerance in Triticum aestivum (wheat) plants. We treated wheat plants with GABA (25 μM) and PEN (15 mg L−1) under saline conditions (0, 100, 200 mM NaCl). Salt stress adversely affected wheat plants' growth and metabolism and caused oxidative stress in wheat plants. GABA, PEN and GABA+PEN were improved growth and salt tolerance in wheat plants that was associated with proline accumulation as compatible osmolyte. Salt stress increased malondialdehyde (MDA) content in Dena cultivar by 5% and 20% and in Ozbec cultivar by 110% and 120%, respectively. MDA level as oxidative stress indicator decreased in stressed wheat plants by GABA, PEN and GABA+PEN treatment, thus GABA and PEN and combined application of GABA and PEN mitigated oxidative stress-induced salt stress in wheat plants. GABA, PEN and GABA+PEN increased ccomponents of enzymatic antioxidant system such as superoxide dismutase, catalase, peroxidase and ascorbate peroxidase in stressed wheat plants. It was observed that the activities of phenylalanine ammonia lyase and tyrosine ammonia-lyase which are involved in phenolics biosynthesis were up-regulated by GABA, PEN and GABA+PEN. GABA, PEN and GABA+PEN activated nitrate reductase as enzyme related to nitrogen metabolism in wheat plants. GABA, PEN and GABA+PEN-mediated improvement in wheat plants was associated with induction of indole-3-acetic acid level (109.69%, 63.58% and 119.58% increase in Ozbec cultivar). Overall, a multifaceted role for GABA and PEN is suggested for minimizing harmful effects of salt stress on wheat plants. These data have laid the basis for future investigations to discover the genetic and molecular mechanisms of GABA and PEN-induced improvement in plant growth during saline conditions.
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