甘蓝型油菜SLG基因片段的克隆及序列分析

Analysis of Self-Incompatibility Locus Gene in Brassica napus

通过不同甘蓝型油菜中SLG基因的克隆及序列分析,探索了甘蓝型油菜中是否存在与芸薹属二倍体中相同或相似的S-locus基因。对10个甘蓝型油菜品种和品系中SLG基因的PCR扩增和序列比较分析发现,这些甘蓝型油菜中都存在第2类的SLG基因,而且,同二倍体芸薹属物种一样,第2类SLG基因之间具有较高的同源性;只有5个甘蓝型油菜品种和品系中存在第一类SLG基因,而且这些基因序列之间表现出高度的保守性,即同源性在96%以上,明显高于不同等位基因之间的同源性。这些甘蓝型油菜中的class I SLG基因可能源于同一个自交不亲和单体。

Self-incompatibility （SI） is one of the most important mechanisms in flowering plants to prevent inbreeding and promoter outcrossing. In Brassica, the diploid varieties of Brassica oleracea （CC） and B. campestris （AA） were self-incompatibility, while the amphidiploid B. napus varieties （AACC） were usually self-compatible. In the SI response, SLG gene was one of the S-locus genes that supposed to contribute to receptor---ligand interactions and signal transduction. SLG gene shares a similarity of 85-98% with eSRK （SRK ectodomain） in the same S haplotype, while in different S haplotypes, the SLGs and SRKs behave differently. In order to make out whether the S-locus exist in B. napus, the SLG gene in the S-locus in several varieties of B. napus were cloned. By PCR analysis and sequences comparison, the class II SLG gene was found in all tested varieties of B. napus, while class I SLG genes were only found in 5 of the 10 tested varieties. Further studies indicated that the five varieties that had the class I SLG genes were probably derived from the same S haploid years ago. The results would provide scientific reference for further study and exploitation on the mechanistic studies of self-compatibility in Brassica napus L.