The causes of reproductive failure under drought stress (DS) are poorly understood. We hypothesized that reproductive failure was related to drought-induced changes in pistil biochemistry. To address this hypothesis, a water deficit-induced experiment was conducted with two cotton cultivars (Dexiamian 1, drought tolerant; Yuzaomian 9110, drought sensitive). Results showed that DS decreased the photosynthesis of subtending leaf and down-regulated sucrose transporter gene (GhSUT-1) expression in pistil for both cultivars, resulting in lower pistil carbon accumulation which was reflected in the decreased starch accumulation. Lower starch, as potential energy, and adenosine triphosphate (ATP), as direct energy, in droughted pistils suggested less energy for pollen tube entrance into ovules, reducing the fertilized ovule number and fertilization efficiency. Further, although pistil peroxidase activity increased under DS, a higher hydrogen peroxide (H2 O2 ) level still was measured in droughted pistils than well-watered pistils, damaging reproductive activities. Moreover, larger decreases in photosynthesis, pistil GhSUT-1 expression, carbon accumulation, starch and ATP contents caused by DS for Yuzaomian 9110 than Dexiamian 1, and different responses of superoxide dismutase and catalase activities, and ascorbic acid and H2 O2 contents to DS between the two cultivars might be the reasons causing a greater decrease in fertilization efficiency for Yuzaomian 9110 than Dexiamian 1 under DS. Thus, we suggest that decreased ovule fertilization under DS was related to the disorganized carbohydrate metabolism and inefficient antioxidant defense in droughted pistils, and the effects of DS on pistil carbohydrate metabolism and antioxidant defense were more significant for drought-sensitive cultivars than drought-tolerant cultivars. This article is protected by copyright. All rights reserved.

中文翻译：

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干旱胁迫对两种不同耐旱棉花品种雌蕊生理及繁殖成功率的影响

人们对干旱胁迫 (DS) 下生殖失败的原因知之甚少。我们假设生殖失败与干旱引起的雌蕊生物化学变化有关。为了解决这一假设，对两个棉花品种（德夏棉 1，耐旱；玉早棉 9110，干旱敏感）进行了缺水诱导试验。结果表明，DS降低了两个品种的对着叶的光合作用，并下调了雌蕊中蔗糖转运蛋白基因（GhSUT-1）的表达，导致雌蕊碳积累减少，这反映在淀粉积累减少上。在干燥的雌蕊中，作为势能的较低淀粉和作为直接能量的三磷酸腺苷 (ATP) 表明花粉管进入胚珠的能量较少，降低受精胚珠数和受精效率。此外，尽管雌蕊过氧化物酶活性在 DS 下增加，但在干旱的雌蕊中仍然测得比充分浇水的雌蕊更高的过氧化氢 (H2 O2) 水平，从而破坏了生殖活动。此外，与德夏面 1 相比，玉早面 9110 的光合作用、雌蕊 GhSUT-1 表达、碳积累、淀粉和 ATP 含量的下降幅度更大，超氧化物歧化酶和过氧化氢酶活性、抗坏血酸和 H2 O2 含量对 DS 的不同响应这两个品种可能是造成鱼枣面9110比德夏面1号在DS下施肥效率下降幅度更大的原因。因此，我们认为DS下胚珠受精减少与干旱雌蕊碳水化合物代谢紊乱和抗氧化防御低下有关，DS对干旱敏感品种的雌蕊碳水化合物代谢和抗氧化防御的影响比耐旱品种更显着。本文受版权保护。版权所有。