非生物逆境胁迫严重威胁果树产业的可持续发展，质膜型(PM)H+-ATPase在非生物胁迫应答中具有重要地位，但分子机制和调控途径不清楚。根据我们的前期研究结果，推测出PM H+-ATPase应答非生物逆境的可能调控途径，即逆境胁迫→MdBT2→MdbHLH104→MdAHA15→PM H+-ATPase→应答。在此基础上，拟采用分子生物学和遗传学及生理生化技术验证该调控途径，并解析各步骤的分子机理。首先鉴定MdbHLH104对MdAHA15的转录激活，然后验证MdBT2与MdbHLH104的互作，并鉴定其对MdbHLH104蛋白的调控作用；验证MdBT2与MdUbiE3-1或MdUbiE3-2的互作，并鉴定二者是否参与MdBT2对MdbHLH104蛋白的调控；最后，通过鉴定MdBT2和MdbHLH104转基因材料的功能，进一步整合该调控途径，揭示其分子机制。

Various abiotic stresses seriously threaten the maintainable development of fruit tree industry. Higher plants including fruit trees have evolved elaborately responsive mechanisms to adapt environmental stresses. Plasma membrane (PM) H+-ATPase is a crucial component of the complicated machinery for stress responses. It is unclear yet, however, concerning the molecular mechanism and regulatory pathway by which PM H+-ATPase responds to abiotic stresses. Our preliminary investigations demonstrated that the expression of PM H+-ATPase gene MdAHA15 is positively induced by multiple stresses, and that bHLH transcription factor MdbHLH104 binds to the promoter region of MdAHA15 gene. Furthermore, MdbHLH104 interacts with a scaffold protein MdBT4, while MdBT4 interacts with two ubiquitin E3 ligases MdUbiE3-1 and MdUbiE3-2, respectively. Therefore, it is reasonable to draw a hypothesis concerning that PM H+-ATPase responds to abiotic stresses via a putatively regulatory pathway, i.e. abiotic stresses→MdBT2(MdUbiE3-1 or MdUbiE3-2)→MdbHLH104→MdAHAs→PM H+-ATPase→stress responses. Based on this hypothesis, various techniques of molecular biology, genetics，biochemistry and physiology will be adopted in this study to further verify this pathway and elucidate the molecular mechanism underlying each step. First of all, several techniques, such as EMSA, ChIP-PCR, transient expression assays and so on, will be conducted to verify if MdbHLH104 really binds to the promoter region of MdAHA15 gene to regulate its expression. Meanwhile, it will be verified if MdBT2 interacts with MdbHLH104 protein to modulate its stability. Furthermore, the interaction between MdBT2 and MdUbiE3-1 or MdUbiE3-2 is to be verified, and the function of MdUbiE3-1 or MdUbiE3-2 in the modulation of MdBT2 in MdbHLH104 protein stability is to be characterized. Finally, the whole regulatory pathway will be integrated, and molecular mechanism will be refined.