Salinity is a major environmental constraint that substantially limits global agricultural productivity. HD-Zip I transcription factors are involved in plant responses to salt stress, but little is known about the HD-Zip I genes in apple (Malus domestica). Here, we characterized the function of an apple HD-Zip I gene (MdHB7-like) and report that its expression is induced by salt stress. To further explore its role in salt stress, we created MdHB7-like overexpressing and RNAi transgenic apple plants. The overexpression of MdHB7-like improved the photosynthetic performance and reduced ROS and Na+ accumulation under salt stress. Plants that overexpressed MdHB7-like also showed increased accumulation of proline and soluble sugars, which may have played an important role in their salt stress tolerance. RNAi suppression of MdHB7-like had the opposite effects. Together, our results demonstrate that MdHB7-like is an important regulator of salt tolerance in apple. Our results provide new insights for future research on the mechanisms by which MdHB7-like promotes salt tolerance and provide a potential target for molecular breeding in apple.

中文翻译：

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HD-Zip I 转录因子 MdHB7 样赋予转基因苹果（Malusdomesica）耐盐性

盐度是一个主要的环境制约因素，它极大地限制了全球农业生产力。HD-Zip I 转录因子参与植物对盐胁迫的反应，但对苹果（Malusdomestica）中的 HD-Zip I 基因知之甚少。在这里，我们表征了苹果 HD-Zip I 基因（MdHB7 样）的功能，并报告其表达是由盐胁迫诱导的。为了进一步探索其在盐胁迫中的作用，我们创建了 MdHB7 样过表达和 RNAi 转基因苹果植物。MdHB7-like 的过表达提高了光合性能并减少了盐胁迫下 ROS 和 Na+ 的积累。过表达 MdHB7 样的植物也表现出脯氨酸和可溶性糖的积累增加，这可能在它们的盐胁迫耐受性中发挥了重要作用。对 MdHB7 样的 RNAi 抑制具有相反的效果。总之，我们的结果表明 MdHB7 样是苹果耐盐性的重要调节剂。我们的研究结果为未来研究 MdHB7-like 促进耐盐性的机制提供了新的见解，并为苹果的分子育种提供了潜在的靶点。