GSK2和NAC016互作共同调控水稻生长和非生物胁迫应答平衡的分子机制

生长发育和逆境应答调控对于作物的生长及产量至关重要，但植物平衡生长-防御的分子机制仍有待进一步揭示。我们前期研究发现：水稻NAC转录因子突变体nac016具有BR信号传导受阻的典型表型，但其抗旱耐盐能力及ABA敏感性增强；NAC016分别与BR信号传导的关键激酶GSK2及ABA信号通路的核心组分SAPK8互作；BR增强NAC016的稳定性，却降低GSK2的稳定性，ABA降低前者却增强后者的稳定性。由此我们推测，GSK2-NAC016作为BR和ABA信号通路的枢纽，调控水稻生长-防御平衡。为证实该推测，本项目拟采用遗传学和分子生物学方法研究二者互作对BR和ABA信号通路的调控；通过体内外磷酸化反应研究GSK2对NAC016的磷酸化修饰；采用ChIP、EMSA及双荧光素酶系统研究NAC016的下游靶基因。研究结果不仅对阐明植物生长-防御的调控机制有重要意义，还将为作物抗逆遗传改良提供科学依据。

Regulation of growth and stress response is crucial for crop growth and yield. However, the molecular mechanism of the growth-defense balance in plant still needs further study. In our previous research, We found that rice NAC transcription factor mutant nac016 has the typical phenotype of defective BR signaling, but has the enhanced drought- and salt-resistance as well as the sensitivity to ABA. Furthermore, NAC016 was found to physically interact with the key kinase GSK2 in BR signaling pathway as well as the core component SAPK8 in ABA signaling pathway, respectively. Exogenous BRs enhanced the stability of NAC016 but reduced that of GSK2 in rice, while the stability of NAC016 decreased and that of GSK2 was increased in the presence of ABA. Based on our results, we hypothesize that GSK2-NAC016 protein complex acts as the hub between BR and ABA signaling pathways. To confirm this speculation, in this study, the genetic interaction between GSK2 and NAC016 will be studied by using multiple mutants. Then, the regulation of BR and ABA signaling pathways by GSK2-NAC016 will be investigated through the export of BR and ABA signals in these mutants. The phosphorylation of NAC016 by GSK2 will be detected by the phosphorylation reaction in vitro and in vivo. Finally, chromatin immunoprecipitation (ChIP) will be performed, and electrophoretic mobility shift assay (EMSA) and double luciferase activity test (LUC/REN) will be used to explore the target genes of NAC016 involved in the growth and abiotic stress response in rice plant. Together, the expected results are not only important for elucidating the regulation mechanism of plant growth-defense, but also provide scientific basis for genetic improvement of crop stress resistance.