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作 者 ：何余堂 涂金星 傅廷栋 陈宝元

期 刊 ：植物学通报 2003年 20卷 05期 页码：513-521

关键词：芸薹属；自交不亲和性；S-基因座；进化模式；

摘 要 ：芸薹属的自交不亲和性是受单基因座、复等位基因控制的孢子体控制型。自交不亲和基因座位（S-locus）是由多个基因组成的复杂区域，称之为S多基因家族，其大多数成员分布于芸薹属的整个染色体组。目前已鉴定出100多个S等位基因，它们的起源分化始于一千万年前。S-座位上存在的多基因有3种：SRK，SLG和SCR/SP11；SRK和SLG在柱头中表达，SCR/SP11在雄蕊中表达。SRK蛋白在识别同类花粉的过程中起主要作用，而SLG蛋白增强了这种自交不亲和反应。SLG与SRK基因中编码S-结构域的核苷酸序列相似性程度高达85％～98%。基因转换可能是SLG和SRK的高度同源性能够得以保持的原因。SRK，SLG和SCR基因紧密相连，并表现出高水平的序列多样性。SRK与SLG基因间的距离很近，在20～25 kb之间。在柱头和花粉中，自交不亲和等位基因之间的共显性关系要比显性和隐性关系更加普遍，这是芸薹属自交不亲和性的一大特点。自交不亲和基因的进化模式存在两种假说：双基因进化模式和中性变异体进化模式；可能存在几种不同的进化方式，它们共同在自然群体中新的S等位基因进化过程中起作用。

Abstract:In Brassica, self-incompatibility was controlled sporophytically by a single, complex S-locus: a complex region with multigenes, so-called S multigene family. Most members of S-multigene family dispersed in Brassica genome. About 100 S-alleles were identified and their differentiation spanned about 10 million years. Three types of genes were identified on S-locus:SRK,SLG and SCR /SP11；SRK and SLG express in stigma and SCR/SP11 in pollen. SRK protein plays the key function in recognization of self-pollen and SLG enhances this function. In all S alleles, SLG and S-domain of SRK has very high DNA sequence similarity: 85%～98%, in the same S-allele. Gene conversion may be the reason of maintainance of high level homology between SLG and SRK.SRK,SLG and SCR linked together in physical map and these genes exhibited high diversity in sequences. Physical distance was about 20～25 kb between SLG and SRK. In Brassica, codominant relationships are more frequent than dominant and recessive ones in both the stigma and the pollen, as one characteristic of SI in Brassica. There were two hypotheses about evolutionary models of SI: two-gene model and neutral-variant model. It may be that several different mechanisms contribute to the evolution of new S-allele specificities in natural populations.

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