Abstract Drought severely restricts global crop yield and quality. These limitations may be partially addressed through genetic engineering to improve crop drought tolerance. The HD-Zip I transcription factors play important roles in the regulation of plant drought tolerance, but their specific functions in the regulation of apple drought response remain unclear. In this study, we found that MdHB-7 was expressed at different levels in a variety of apple tissues and was significantly induced by abscisic acid (ABA) and drought stress treatments. To investigate the functions of MdHB-7, we created transgenic apple plants that exhibited either MdHB-7 overexpression or RNAi-induced MdHB-7 suppression. Through drought stress treatments and phenotypic assessments, we found that MdHB-7 expression enhanced the drought tolerance of apple plants. Overexpression of MdHB-7 promoted endogenous ABA accumulation, stomatal closure, and reactive oxygen species (ROS) detoxification in response to drought, whereas suppression of MdHB-7 expression had the opposite effect. Our results lay a foundation for further research on the mechanisms by which HD-Zip I proteins promote drought tolerance.

中文翻译：

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HD-Zip I 转录因子 MdHB-7 调节转基因苹果的耐旱性

摘要 干旱严重制约着全球作物产量和品质。这些限制可以通过基因工程来部分解决，以提高作物的耐旱性。HD-Zip I转录因子在调节植物耐旱性中起重要作用，但它们在调节苹果干旱反应中的具体功能尚不清楚。在本研究中，我们发现 MdHB-7 在多种苹果组织中均有不同水平的表达，并且受到脱落酸 (ABA) 和干旱胁迫处理的显着诱导。为了研究 MdHB-7 的功能，我们创建了表现出 MdHB-7 过表达或 RNAi 诱导的 MdHB-7 抑制的转基因苹果植物。通过干旱胁迫处理和表型评估，我们发现 MdHB-7 表达增强了苹果植物的耐旱性。MdHB-7 的过表达促进了内源性 ABA 积累、气孔关闭和响应干旱的活性氧 (ROS) 解毒，而抑制 MdHB-7 表达则具有相反的效果。我们的结果为进一步研究 HD-Zip I 蛋白促进耐旱性的机制奠定了基础。