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چکیده
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Background and Aim: Water deficit is one of the most important abiotic stresses that reduces crop productivity. Barley is one of the earliest domesticated cereal crops and ranks as the fourth most important grain globally in terms of nutritional and forage significance. The aim of this study was to investigate the effects of selenium nanoparticles and the mycorrhizal fungus Piriformospora indica on drought tolerance in two barley genotypes (Yousef as tolerant and Morocco as sensitive genotype). Methods: A greenhouse experiment was conducted in a factorial design within completely randomized blocks with three replicates with emphasis on evaluating growth-related traits and biochemical indices. These parameters were measured in two barley genotypes in response to selenium nanoparticles application (3 and 6 mg/l, 3 times at 10-day intervals) and Piriformospora indica inoculation, under three drought levels (70, 30 and 10% of the field capacity). Results: Results showed that drought stress led to reduction of growth-related traits especially in the sensitive genotype, but a significant increase in H2O2 and MDA. The application of selenium nanoparticles particularly at 6 mg/l, and inoculation of Piriformospora indica improved growth and increased biochemical parameters (chlorophyll, carotenoid, proline, total carbohydrate and protein contents and also antioxidant enzyme activities (ascorbate peroxidase, superoxide dismutase, glutathione S-transferase, and peroxidase) in the studied genotypes under drought stress. In addition, results demonstrated that selenium nanoparticles caused upregulation of the DREB2A gene, and Piriformospora indica led to the induction of DREB2A and DREB2B gene expression. The DREBs is one of the key transcription factors specific to the plant kingdom and contribute to upregulation of genes involved in antioxidant mechanisms, water relations, and growth-related traits in the studied genotypes. Conclusion: The results from this study revaluated that application of selenium nanoparticles and Piriformospora indica inoculation could moderate drought negative effects in two barley genotypes
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