蛋白激酶PPCK-like通过调控PPC3提高葡萄碱性盐抗性的机理研究

针对土壤碱性盐危害严重但缺乏抗碱性盐砧木的实际需求，围绕根系有机酸合成及分泌是抗碱性盐的基本途径这一科学问题，依托葡萄根系主要合成草酸及PPCK-like和PPC3的初步功能鉴定等前期研究结果，本项目重点开展以下研究：（1）鉴定PPCK-like的丝氨酸/苏氨酸蛋白激酶功能，阐明其在碱性盐胁迫下能调控根系草酸合成、提高碱性盐抗性；（2）阐明PPC3提高根系草酸合成和碱性盐抗性的功能，鉴定其关键磷酸化位点，明确磷酸化修饰与其酶活性的关系；（3）解析PPCK-like调控途径，即阐明PPCK-like磷酸化PPC3蛋白，提高PPC3活性，促进草酸合成，并评价PPC3在该途径中的贡献。预期研究结果将揭示一条以“PPCK-like–PPC3–草酸合成”为主线的抗碱性盐分子途径，丰富根系中有机酸参与的碱性盐抗性机制，也有助于草酸合成调控在葡萄抗碱性盐砧木分子育种上的应用。

Alkaline salt causes serious harm to crops, however the rootstocks tolerant to alkalinity are absent. Biosynthesis and secretion of organic acids is a fundamental way to resist alkaline stress. Additionally, oxalate was indicated to be the primary organic acid in grapevine roots and the preliminary experiments about function identification of PPCK-like and PPC3 were performed in our previous studies. Based on the above research background, the primary studies of this project will be focused on the following aspects: (1) The function of PPCK-like as a Ser/Thr protein kinase will be identified, and its role in regulating oxalate biosynthesis and tolerance to alkaline stress will be elucidated. (2) The role of PPC3 in increasing oxalate biosynthesis and alkaline stress tolerance will be disclosed; additionally, the key phosphorylation site of PPC3 will be identified; moreover, the association between phosphorylation level and enzyme activity of PPC3 will be elucidated. (3) The regulatory pathway of PPCK-like will be unraveled, i.e., PPCK-like enhances oxalate synthesis via increasing PPC3 phosphorylation level and enzyme activity; additionally, the contribution of PPC3 in the PPCK-like–mediated pathway will be evaluated. Collectively, the expected results will disclose the molecular pathway of “PPCK-like−PPC3-oxalate synthesis” that is related to alkaline stress tolerance, enrich the studies related to organic acid-mediated alkaline salt tolerance, and favor the application of oxalate synthesis regulation in molecular breeding of grapevine rootstocks with high tolerance to alkaline salt.