State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, P.R. China.
Institute for Advanced Studies, Wuhan University, Wuhan, P.R. China.
J Exp Bot. 2021 Feb 2;72(2):592-607. doi: 10.1093/jxb/eraa449.
The phytohormone abscisic acid (ABA) is involved in various plant processes. In response to drought stress, plants quickly accumulate ABA, but the regulatory mechanism of ABA accumulation is largely unknown, especially in woody plants. In this study, we report that MdMYB88 and MdMYB124 are myeloblastosis (MYB) transcription factors critical for ABA accumulation in apple trees (Malus x domestica) following drought, and this regulation is negatively controlled by ABA. MdMYB88 and MdMYB124 positively regulate leaf water transpiration, photosynthetic capacity, and stress endurance in apple trees under drought conditions. MdMYB88 and MdMYB124 regulate the expression of biosynthetic and catabolic genes of ABA, as well as drought- and ABA- responsive genes. MdMYB88 associates with promoter regions of the ABA biosynthetic gene 9-cis-epoxycarotenoid dioxygenase 3 (NCED3). Finally, expression of MdMYB88 and MdMYB124 is repressed by ABA. Our results identify a feedback regulation of MdMYB88 and MdMYB124 in modulating ABA homeostasis in apple trees.
植物激素脱落酸（ABA）参与各种植物过程。植物对干旱胁迫迅速积累 ABA，但 ABA 积累的调节机制在很大程度上尚不清楚，尤其是在木本植物中。本研究报告称，MdMYB88 和 MdMYB124 是苹果（Malus x domestica）中与干旱胁迫下 ABA 积累相关的髓细胞白血病（MYB）转录因子，该调节受 ABA 的负调控。MdMYB88 和 MdMYB124 正向调控苹果在干旱条件下叶片水分蒸腾、光合作用和抗逆能力。MdMYB88 和 MdMYB124 调节 ABA 生物合成和分解代谢基因以及干旱和 ABA 响应基因的表达。MdMYB88 与 ABA 生物合成基因 9-顺式-环氧类胡萝卜素双加氧酶 3（NCED3）的启动子区域结合。最后，ABA 抑制 MdMYB88 和 MdMYB124 的表达。我们的研究结果确定了 MdMYB88 和 MdMYB124 在调节苹果树 ABA 动态平衡中的反馈调节。
