MdGH3.6 is targeted by MdMYB94 and plays a negative role in apple water-deficit stress tolerance

第一作者：Lijuan Jiang

第一单位：西北农林科技大学

第一通讯：Qingmei Guan

 Abstarct 

背景回顾：Drought significantly limits apple fruit production and quality. Decoding the key genes involved in drought stress tolerance is important for breeding varieties with improved drought resistance. 

干旱严重限制苹果果实的产量和质量。解码干旱胁迫耐受性的关键基因对于抗干旱品种的育种研究是非常重要的。

主要发现：Here, we identified GRETCHEN HAGEN3.6 (GH3.6), an indole-3-acetic acid (IAA) conjugating enzyme, to be a negative regulator of water-deficit stress tolerance in apple. 

本文中，作者发现吲哚-3-乙酸（IAA）酰胺合成酶GH3.6（功能：催化氨基酸与IAA形成IAA的氨基轭合物, 发挥暂时或永久灭活IAA的作用。）是苹果水分不足胁迫耐受性的负调控因子。

结果1-MdGH3.6功能：Overexpressing MdGH3.6 reduced IAA content, adventitious root number, root length and water-deficit stress tolerance, whereas knocking down MdGH3.6 and its close paralogs increased IAA content, adventitious root number, root length and water-deficit stress tolerance. 

过表达MdGH3.6会降低IAA的含量，减少侧根的数量和根长，减弱对水分不足胁迫的耐受性；而MdGH3.6及其近缘旁系同源基因的敲低表型完全相反。

结果2-MdGH3.6下游～蜡合成：Moreover, MdGH3.6 negatively regulated the expression of wax biosynthetic genes under water-deficit stress and thus negatively regulated cuticular wax content. 

此外，MdGH3.6能够在水分不足的胁迫条件下，负调控蜡合成基因的表达，从而负调控植株表皮的蜡含量。

结果3-MdGH3.6下游～ROS：Additionally, MdGH3.6 negatively regulated reactive oxygen species scavengers, including antioxidant enzymes and metabolites involved in the phenylpropanoid and flavonoid pathway in response to water-deficit stress. 

另外，MdGH3.6还会在响应水分不足胁迫时，负调控活性氧物质（ROS）清除剂，包括抗氧化酶和参与苯丙烷和类黄酮通路的代谢物。

结果4-MdGH3.6上游～MYB94：Further study revealed that the homolog of transcription factor AtMYB94, rather than AtMYB96, could bind to the MdGH3.6 promoter and negatively regulated its expression under water-deficit stress conditions in apple. 

进一步的研究揭示了AtMYB94，而非AtMYB96的同源基因，能够结合到MdGH3.6基因的启动子区，负调控该基因在苹果遭遇水分不足胁迫时的表达。

结论：Overall, our results identify a candidate gene for the improvement of drought resistance in fruit trees.

综上，本文的研究结果揭示了一个未来可用于改良果树干旱抗性的候选基因。

** 管清美 **

doi: https://doi.org/10.1111/tpj.15631

Journal: the plant journal

First Published: December 17, 2021