Yang Fei, Zhao Ling-Ling, Song Lai-Qing, Han Yuepeng, You Chun-Xiang, An Jian-Ping
Apple Technology Innovation Center of Shandong Province, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, 271018, Shandong, China.
Yantai Academy of Agricultural Sciences, Yan-Tai 265599, Shandong, China.
Hortic Res. 2024 Jan 30;11(4):uhae029. doi: 10.1093/hr/uhae029. eCollection 2024 Apr.
ABSCISIC ACID-INSENSITIVE5 (ABI5) is a core regulatory factor that mediates the ABA signaling response and leaf senescence. However, the molecular mechanism underlying the synergistic regulation of leaf senescence by ABI5 with interacting partners and the homeostasis of ABI5 in the ABA signaling response remain to be further investigated. In this study, we found that the accelerated effect of MdABI5 on leaf senescence is partly dependent on MdbHLH93, an activator of leaf senescence in apple. MdABI5 directly interacted with MdbHLH93 and improved the transcriptional activation of the senescence-associated gene by MdbHLH93. MdPUB23, a U-box E3 ubiquitin ligase, physically interacted with MdABI5 and delayed ABA-triggered leaf senescence. Genetic and biochemical analyses suggest that MdPUB23 inhibited MdABI5-promoted leaf premature senescence by targeting MdABI5 for ubiquitin-dependent degradation. In conclusion, our results verify that MdABI5 accelerates leaf senescence through the MdABI5-MdbHLH93- regulatory module, and MdPUB23 is responsible for the dynamic regulation of ABA-triggered leaf senescence by modulating the homeostasis of MdABI5.
脱落酸不敏感5（ABI5）是介导脱落酸信号响应和叶片衰老的核心调控因子。然而，ABI5与相互作用伙伴协同调控叶片衰老的分子机制以及ABI5在脱落酸信号响应中的稳态仍有待进一步研究。在本研究中，我们发现MdABI5对叶片衰老的加速作用部分依赖于苹果叶片衰老的激活因子MdbHLH93。MdABI5直接与MdbHLH93相互作用，并增强了MdbHLH93对衰老相关基因的转录激活。MdPUB23是一种U-box E3泛素连接酶，与MdABI5发生物理相互作用，并延缓了脱落酸诱导的叶片衰老。遗传和生化分析表明，MdPUB23通过靶向MdABI5进行泛素依赖性降解，从而抑制MdABI5促进的叶片早衰。总之，我们的结果证实，MdABI5通过MdABI5-MdbHLH93调控模块加速叶片衰老，而MdPUB23通过调节MdABI5的稳态负责对脱落酸诱导的叶片衰老进行动态调控。
