The aim of this study was to investigate the effects of drought stress on oxidative damage and efficiency of PSII photochemistry in barley and compare the varietal response of different genotypes including Yusof (tolerant), Moroc9-75 (sensitive), and wild barley (HS) to drought. Plants were subjected to different levels of soil water availability including control, moderate, and severe drought stress. Exposure to drought stress led to decrease in leaf water potential, biomass production, and stomatal conductance (g s ) in all genotypes. Drought induced an increase in H 2 O 2 content followed by increase in malondialdehyde (MDA) as a final result of lipid peroxidation. Drought stress also resulted in reduction of D1 protein content in all genotypes and decreased the maximal quantum yield of PSII photochemistry (F V /F M ). These parameters were more affected in Moroc9-75 cultivar by drought stress compare to Yusof and HS genotype. Based on our results, drought-induced reactive oxygen species may decrease PSII photochemistry either through peroxidation of thylakoid membranes or interfering with D1 protein synthesis, necessary for proper function of PSII.

中文翻译：

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中度和重度干旱胁迫与氧化应激相关的野生和栽培大麦基因型 D1 蛋白含量和量子产量的差异变化

本研究的目的是研究干旱胁迫对大麦氧化损伤和 PSII 光化学效率的影响，并比较不同基因型的品种反应，包括 Yusof（耐受）、Moroc9-75（敏感）和野生大麦 (HS)到干旱。植物受到不同水平的土壤水分可用性的影响，包括控制、中度和严重干旱胁迫。暴露于干旱胁迫导致所有基因型的叶水势、生物量产生和气孔导度 (gs) 降低。干旱导致 H 2 O 2 含量增加，随后丙二醛 (MDA) 增加，这是脂质过氧化的最终结果。干旱胁迫还导致所有基因型中 D1 蛋白含量降低，并降低 PSII 光化学的最大量子产率 (FV /FM )。与 Yusof 和 HS 基因型相比，这些参数在 Moroc9-75 品种中受干旱胁迫的影响更大。根据我们的结果，干旱诱导的活性氧可能通过类囊体膜的过氧化或干扰 D1 蛋白合成来降低 PSII 光化学，这对于 PSII 的正常功能是必不可少的。