Jasmonic acid (JA) is shown to induce leaf senescence. However, the underlying molecular mechanism is not well understood, especially in woody plants such as fruit trees. In this study, we are interested in exploring the biological role of MdBT2 in JA‐mediated leaf senescence. We found that MdBT2 played an antagonistic role in MdMYC2‐promoted leaf senescence. Our results revealed that MdBT2 interacted with MdMYC2 and accelerated its ubiquitination degradation, thus negatively regulated MdMYC2‐promoted leaf senescence. In addition, MdBT2 acted as a stabilizing factor to improve the stability of MdJAZ2 through direct interaction, thereby inhibited JA‐mediated leaf senescence. Furthermore, our results also showed that MdBT2 interacted with a subset of JAZ proteins in apple, including MdJAZ1, MdJAZ3, MdJAZ4 and MdJAZ8. Our investigations provide new insight into molecular mechanisms of JA‐modulated leaf senescence. The dynamic JA‐MdBT2‐MdJAZ2‐MdMYC2 regulatory module plays an important role in JA‐modulated leaf senescence.

中文翻译：

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苹果BT2蛋白通过调节MYC2和JAZ2的稳定性来负面调节茉莉酸触发的叶片衰老

茉莉酸（JA）已显示可诱导叶片衰老。然而，潜在的分子机制还没有被很好地理解，尤其是在木本植物如果树中。在这项研究中，我们有兴趣探索MdBT2在JA介导的叶片衰老中的生物学作用。我们发现MdBT2在MdMYC2促进的叶片衰老中起拮抗作用。我们的结果表明，MdBT2与MdMYC2相互作用并加速其泛素化降解，从而对MdMYC2促进叶片衰老产生负调控作用。此外，MdBT2充当稳定因子，通过直接相互作用改善MdJAZ2的稳定性，从而抑制JA介导的叶片衰老。此外，我们的结果还表明，MdBT2与苹果中的JAZ蛋白子集相互作用，包括MdJAZ1，MdJAZ3，MdJAZ4和MdJAZ8。我们的研究为JA调控的叶片衰老的分子机制提供了新的见识。动态JA‐MdBT2‐MdJAZ2‐MdMYC2调节模块在JA调制的叶片衰老中发挥重要作用。