MAPK级联途径介导杂交杨抗锈菌PCD形成机理

Rust caused by Melampsora larici-populina is the main disease of poplar plantation. The existing poplar varieties could not prevent the infection of E4 rust, but one tolerant hybrid poplar could delay the harm caused by rust through producing PCD. Preliminary studies indicated that the functional activation of R genes and related transcription regulation factors of the hybrid poplar were mediated by MAPK cascade signaling pathway, and closely related to the promotion of PtdMKK7. Based on these results, the mechanism of MAPK mediated PCD will be studied from 3 aspects: Firstly, the phosphorylation activity of PtdMKK7 will be studied by methods such as point mutation, in vitro phosphorylation, etc. Secondly, the substrate of PtdMKK7 will be identified by methods such as full-length transcriptional sequencing, yeast two-hybrid system, BiFC, etc. Lastly, the relevance of the PCD defense response and PtdMKK7 will be appraised through the methods of transient expression of tobacco, in-gel kinase assay, CRISPR/Cas9 gene editing technique, trypan blue staining, TUNEL, etc. Then, based on omics studies such as transcriptome, metabolome, genome, etc., the mechanism of MAPK cascade pathway mediated PCD during the hybrid poplar against rust will be revealed systematically. This study will provide a theoretical basis for accelerating the process of resistant poplar breeding, and provide technical support for the prevention and treatment of poplar leaf rust.

落叶松-杨栅锈菌引起的杨树叶锈病是杨树的主要病害。现有杨树品种无法阻止E4锈菌侵染，但“耐病”杂交杨可通过产生PCD延缓锈菌危害。前期研究表明该杂交杨R基因及其TF因子功能活化受MAPK级联途径介导，且与PtdMKK7基因表达上调密切相关。在此基础上，本项目拟对MAPK级联途径介导杂交杨抗锈菌PCD形成机理进行三个层次的研究，即：应用点突变和体外磷酸化等技术鉴定PtdMKK7的磷酸化活性等功能；应用全长转录本测序、酵母双杂交和BiFC等技术鉴定PtdMKK7底物；应用烟草瞬时表达、胶内激酶活性、基因编辑、台盼蓝染色及TUNEL等技术鉴定PtdMKK7及其底物与杂交杨抗锈菌PCD形成关系，并应用转录组、代谢组和基因组等多组学分析MAPK级联途径介导PCD的多基因协同效应。进而系统揭示MAPK级联途径介导杂交杨抗锈菌PCD形成机理，为加速抗病育种进程提供理论依据，为防治杨树叶锈病提供技术保障。

落叶松-杨栅锈菌引起的杨树叶锈病是杨树的主要病害。现有杨树品种无法阻止E4锈菌侵染，但“耐病”杂交杨可通过产生PCD延缓锈菌危害。前期研究表明该杂交杨R基因及其TF因子功能活化受MAPK级联途径介导，且与PtdMKK7基因表达上调密切相关。本项目旨在此基础上研究介导杂交杨PCD形成的PtdMKK7及其下游分子以及机制。我们的研究结果表明MKK7-MPK4.1参与杂交杨抗锈菌中H2O2积累和PCD的形成。MKK7上游激酶为MAP3和MEKK19。利用磷酸化组筛到WRKY、ERF等MKK7-MPK4.1的磷酸化底物鉴定了可能的磷酸化位点。此外，我们还对比了亲和型互作中MKK7-MPK4.1路径激活状况，发现E4锈菌侵染后1815杨的MKK7-MPK4.1路径未被有效激活，暗示MKK7-MPK4.1路径可能是杨树抗病信号传导的关键信号通路。研究结果对杨树应答病原侵染的免疫信号路径研究有一定的参考价值。