桃自交亲和性的分子机制及遗传特性研究

 以油桃（Prunus persicavar.necturina）‘中油5号’及其自交后代为试材，利用花柱S-RNase基因和花粉SFB基因的特异性引物进行PCR扩增，对扩增片段进行回收、克隆、测序和Blast分析，确定了‘中油5号’的自交不亲和基因型为S₁S_2(m)。序列分析结果显示，‘中油5号’桃S₁-RNase和S_2(m)-RNase与多个其他李属S-RNase基因氨基酸和核苷酸序列间都具有极高的相似性，SFB₁和SFB₂基因与多个其他李属SFB基因氨基酸和核苷酸序列间也都具有极高的相似性。进一步对‘中油5号’自交后代个体的S基因型进行检测，发现后代群体中存在3种S基因型，分别为S₁S₁、S₁S_2(m)和S_2(m)S_2(m)，且分离比为8︰13︰7，与预期的比例1︰2︰1差异不显著（χ² = 0.214 < χ²_0.05,2 = 5.991），说明S-RNase基因和SFB基因都遵循两因素的孟德尔遗传规律进行连锁分离。此外，基因型为S₁S₁和S_2(m)S_2(m)的纯合体的存在，表明桃花粉SFB₁和SFB₂基因均不能被自身花柱S-RNase所识别，这是由于SFB₁和SFB₂基因翻译提前终止所造成的，从而使‘中油5号’表现出自交亲和性。

Molecular Mechanism and Genetic Characterization of Self-compatibility in Peach

PCR were performed with specific primer sets of Prunus S-RNase and SFB alleles using ‘Zhongyou 5’(Prunus persica var.necturina)as the template.The amplification products were extracted,cloned,sequenced and then Blast analysis,which were used to determine the S-genotype of this cultivar,S1S2(m).Sequence analysis showed that Prunus persica S1-RNase and S2(m)-RNase alleles have exceptionally high identities with other Prunus S-RNase alleles,and,SFB1 and SFB2 alleles have exceptionally high identities with other Prunus SFB alleles,too.The S-genotypes of self-pollinated progeny of‘Zhongyou 5’were detected,it is obviously that three classes were found in progeny,and the segregation ratio of S1S1,S1S2(m)and S2(m)S2(m)was 8︰13︰7,which did fit to the expected ratio that was 1︰2︰1(χ2 = 0.214 < χ20.05,2 = 5.991).This result showed that S-RNase and SFB alleles are tightly co-segregation according to the Mendel genetic model.Moreover,the existence of S1S1 and S2(m)S2(m) homozygotes suggested that SFB1and SFB2could not be cognized by self S-RNase,due to that the protein of these two SFB alleles were premature,which resulted in the‘Zhongyou 5’is self-compatible.