BbCNB通过调控碳流分配提高棉花耐盐性的作用机制

To improve salt-tolerance in cotton is greatly important for both utilization of saline-alkali soil and sustaining cotton production. In our previous work, salt tolerance of cotton was significantly improved by overexpressing a B subunit of calcineurin from Beauveria bassiana (BbCNB). Notably, contents of proline and protein content were increased while that of oil was decreased in the seeds. Results of real-time PCR and digital gene expression suggest that BbCNB is possibly involved in the carbon partitioning through regulating phosphoenolpyruvate carboxylase. However, the mechanism is not clear until now. Hence, this research aims to study 1) the mechanism of BbCNB in regulating expression of PEPC; 2) roles of BbCNB in phosphorylation and ubiquitin-mediated degradation of PEPCK; 3) the relationship between BbCNB and synthesis of proline. The research will elucidate mechanism of BbCNB and its target protein in regulating carbon partitioning during synthesis of proteins and oil in cotton. Moreover, it will be addressed that why salt-tolerance of cotton can be improved by overexpressing BbCNB. This will further assist us to understand the mechanism of the salt-tolerance improvement and how it can be used for cultivation and breeding in cotton.

提高棉花耐盐性，对充分利用盐碱地资源，稳定棉花生产有重要意义。项目组将球孢白僵菌的钙调磷酸酶B亚基编码基因BbCNB转入棉花，棉花耐盐性显著提高，同时发现转基因棉花脯氨酸含量增加，种子蛋白质含量明显上升而含油量下降。Real-time PCR和表达谱分析结果暗示，钙调磷酸酶可能通过调控磷酸烯醇式丙酮酸羧化酶（PEPC）参与棉花的碳流分配，但具体作用机制尚不清楚。在前期研究基础上，本项目拟进一步研究BbCNB调控PEPC表达的分子机理，及BbCNB对磷酸烯醇式丙酮酸羧激酶（PEPCK）磷酸化和泛素化降解的影响；研究BbCNB与脯氨酸合成的关系；进而解析BbCNB与下游靶蛋白参与调节碳流在植株油脂-蛋白合成中的分配机制，探究表达BbCNB提高棉花耐盐性的分子机理。本研究对拓宽我们认识BbCNB提高植物耐盐性的机理有理论价值，其研究结果对盐碱地条件下棉花的栽培与育种也有指导意义。

提高棉花耐盐性，对充分利用盐碱地资源，稳定棉花生产有重要意义。项目组前期将球孢白僵菌的钙调磷酸酶B亚基编码基因BbCNB转入棉花，棉花耐盐性显著提高，同时发现转基因棉花脯氨酸含量增加，种子蛋白质含量明显上升而含油量下降。本项目拟解析BbCNB与下游靶蛋白参与调节碳流在植株油脂-蛋白合成中的分配机制，探究表达BbCNB提高棉花耐盐性的分子机理。本项目通过基因功能验证发现钙调磷酸酶A亚基BbCNA和棉花内源的钙调磷酸酶也因GhCBL1也可以提高棉花耐盐性；同时进一步验证了盐胁迫或超量表达钙调磷酸酶会引起种子碳氮分配的变化，结合转录组学、蛋白组学和磷酸化修饰组学分析发现，盐胁迫或超量表达钙调磷酸酶相关基因后，钙调磷酸酶可能通过其对应的钙调磷酸酶激酶（CIPKs）磷酸化下游的底物蛋白（乙酰-CoA 羧化酶编码基因等），从而导致种子含油量下降，蛋白质含量上升。下一步拟对相关靶基因进行功能分析，希望揭示种子油脂合成基因参与应答盐碱胁迫的分子机制。通过该研究创建了耐盐的棉花种质资源，其研究结果对盐碱地条件下棉花的栽培与育种也有指导意义。