水杨酸生物合成调控嫁接西瓜低温抗性的机制研究

Grafting plays an important role in the resistance of watermelon plants to low temperature, while salicylic acid (SA) as a signal molecule, also has been found to induce plant resistance to low temperature; however, the specific mechanism is still not clear. In recent years, the applicant has found that redox signaling is involved in the regulation of plant photosynthesis and stress responses by plant hormone like brassinosteroids (BRs), other studies have found that changes in SA synthesis and subsequently induced cellular redox response play important roles in plant cold resistance. Therefore, the applicant proposes the hypothesis that the synthesis, transport and transformation of SA in grafted plants contributed to cold resistance by activating the CBF signaling pathways downstream of redox signal. By using HPLC, Western blot and qRT-PCR, the project is aimed at clarifying the action mechanism of endogenous and exogenous SA-regulated cold resistance. The project will also illuminate the SA-mediated signal transduction pathways and molecular mechanism in cold resistance of watermelon grafted onto pumpkin by using RNA-seq and 2-DE technology, combined with the redox analysis. Finally, the project is expected to provide a theoretical basis for the efficient use of cold-resistant rootstock resources and the chemical regulation of crop cold resistance.

采用适宜砧木嫁接可提高西瓜对低温逆境的抗性，而水杨酸（SA）作为一种信号分子也可以诱导植物对低温等非生物逆境的抗性，但具体机制仍不清楚。申请者近年来研究发现，氧化还原（redox）信号介导了油菜素内酯（BRs）等植物激素对植物光合作用和抗逆反应的调控；同时，SA合成响应及其诱导的细胞redox状态的变化在植物低温抗性中发挥重要作用。因而我们提出嫁接植株中SA的合成、运输和转换，可能通过改变细胞redox状态，并激活下游CBF信号途径来介导植物的低温抗性。本项目拟以西瓜为材料，利用HPLC、Western blot和qRT-PCR等技术明确内源与外源SA调控西瓜低温抗性的作用机制；并以西瓜、南瓜为材料构建不同嫁接组合，通过RNA-seq和2-DE等技术，结合redox相关分析阐明SA在嫁接诱导西瓜低温抗性中的信号转导途径及分子机制，以期为耐低温砧木资源高效利用和作物低温抗性调控提供理论依据。

低温冷害是我国西甜瓜生产中发生概率最高的灾害，本项目研究了内源与外源水杨酸（SA）调控西瓜低温抗性的作用机制，发现了细胞氧化还原（redox）信号和CBF响应途径在SA诱导的西瓜低温抗性中发挥重要作用。并以西瓜、南瓜为材料构建不同嫁接组合，阐明了SA在南瓜砧木嫁接诱导西瓜低温系统获得性适应性中的信号调控机制。通过嫁接西瓜响应低温的蛋白组学研究，解析了南瓜砧木嫁接诱导西瓜低温抗性的分子调控机制。并结合转录组测序和BLAST分析，初步鉴定了南瓜砧木向西瓜接穗长距离转运的低温响应mRNA/蛋白。以上研究结果丰富了西瓜低温逆境响应的理论知识，为西瓜品种改良和提高西瓜低温适应性提供了新的途径，也为瓜类作物耐低温性遗传改良提供了重要的候选基因信息。