甘蓝型油菜BnSCR基因功能和自交亲和性分子机理的研究

Self-incompatibility is a natural fertilization barrier to prevent self-pollination and promote cross-fertilization so that plant can increase its adaptability to the environments. It has been utilized widely in hybrid breeding in Brassica rapa and Brassica oleracea. Although Brassica rapa and Brassica oleracea are self-incompatible and Brassica napus has the stigma determinant S-locus receptor kinase gene (SRK) and the pollen determinant S-locus cysteine-rich protein (SCR) gene, Brassica napus is self-compatible. Focusing on the scientific issue, we have done some researches by genetic analysis, gene cloning and gene expression. The results have indicated that SCR plays a key role in Brassica napus self-compatibility. Based on the previous researches, this proposal will show gene functions of BnSCR-7 and BnSCR-6 in self-incompatibility by pollination test, gene expression, genetic transformation and gene cloning and further will give some knowledge of self-compatibility in Brassica napus. The results will rich the understanding of self-incompatibility and of trait changes during the evolutionary process of plant polyploidization, and also will prompt the utilization of self-incompatibility in Brassica napus hybrid breeding program.

自交不亲和是植物防止自交、促进异交以增强环境适应力的一种自然生殖特性，广泛用于白菜和甘蓝的杂种选育。白菜和甘蓝为自交不亲和，甘蓝型油菜有S位点（S单倍型）花粉识别基因BnSCR和柱头识别基因BnSRK，却为自交亲和。针对这一科学问题，申请人多年来进行遗传分析、基因克隆和表达分析，结果表明BnSCR基因是甘蓝型油菜亲和性的关键。在此基础上，本项目以S单倍型BnS-1300/BnS-6自交不亲和系“S-1300"、BnS-7/BnS-6自交亲和系 “230”和“326”为材料，通过授粉实验、基因表达、遗传转化实验、基因克隆等技术分析BnSCR-7和BnSCR-6基因功能，揭示BnS-7/BnS-6甘蓝型油菜自交亲和的分子机制。本项目的实施，将丰富对自交不亲和现象和植物多倍化过程中性状改变的认识、促进甘蓝型油菜自交不亲和杂种优势利用，具有重要的理论意义和实践价值。

自交不亲和是植物界防止自交、促进异交以增强适应外界环境能力的一种自然现象，是甘蓝型油菜杂种优势利用的重要途径之一。但是自然存在的甘蓝型油菜自交亲和。根据自交不亲和系“S-1300”与不同油菜杂交后F1代的表型差异，将自然存在的甘蓝型油菜分为了显性自交亲和与隐形自交亲和两类，显性亲和的甘蓝型油菜是由于BnSCR-1启动子区有一转座子插入导致的BnSCR-1不表达，从而表现出自交亲和，但是隐性亲和的自交亲和机理一直没有深入研究。本项目通过不同材料中基因的克隆、表达分析和转基因手段发现在甘蓝型油菜中BnSCR-6和BnSCR-7基因序列比较保守，仅在基因上游有少量突变，但BnSCR-6和BnSCR-7在不同材料中表达量均较低；而且在油菜中直接的超表达BnSCR-6或BnSCR-7基因，并不能恢复油菜自交不亲和的表型，但超表达的BnSCR-6能够产生正常的BnSCR-6蛋白识别BnSRK-6或BnSRK-1300引起自交不亲和反应；在隐性亲和油菜中，BnSCR-6和BnSCR-7的表达量低是由于BnSmi和BnSmi2的影响所致，敲除“326”中的BnSmi2能够产生自交不亲和的转基因后代；甘蓝型油菜中Ⅱ类S单倍型BnS-1300、BnS-7和BnS-6的显隐性关系为：BnS-1300=BnS-6>BnS-7。进一步研究Smi类基因与BnSCR间的关系将有助于揭示甘蓝型油菜自交亲和的这一重大进化问题。项目有关研究结果在SCI刊物发表论文6篇，培养博士研究生3名，硕士研究生2名，在读博士生3名。