中国梨2个自交不亲和新等位基因(S等位基因)的分子鉴定

自交不亲和是显花植物的一种重要生殖生理现象,为探明中国梨的自交不亲和特性,对‘锦香’(Pyrus bretschneideri cv. Jinxiang)和‘鹅酥’(Pyrus bretschneideri cv. Esu)2个中国梨品种进行了基因组PCR特异扩增、S基因序列分析及田间杂交授粉试验。结果确定它们各含1个新S-RNA酶基因,分别命名为S37-和S38-RNase,GenBank序列号为DQ839238和DQ839239。生物信息学分析结果表明,S37-和S38-RNA酶的推导氨基酸序列与S1-至S36-RNA酶36个梨S基因具有相同的、高度保守的C1和C2区,但其高变区与S1-至S36-RNA酶差异较大,其中与S15的差异最小,只有3个氨基酸不同。在推导的氨基酸水平上,S37与S38有96%的序列相似性,但两者与S15的相似性更高,皆为98%,与S32的相似性最低,都只有63%;S37和S38的内含子较大,分别为786bp和723bp,与S15的777bp大小接近。最后,经分析验证确定‘锦香’和‘鹅酥’的S基因型分别为S34S37和S15S38。

Molecular Identification of Two New Self-incompatible Alleles(S-alleles)in Chinese Pear(Pyrus bretschneideri)

Self-incompatibility (SI) is an important intraspecific reproductive barrier in flowering plants. To identify the S-alleles of Chinese pear species (Pyrus pyrifolia, P. bretschneideri, P. ussuriensis and P. sinkiangenis etc.), S-RNase-specific PCR amplification, sequence analyses and field pollination tests were performed using two cultivars 'Jingxiang' and 'Esu' of P. bretschneideri as materials. Two new S-RNase genes were identified from the two cultivars. They were 1,122 bp and 1,058 bp in length, and designated as S37-RNase (GenBank accession no. DQ839238) and S38-RNase (GenBank accession no. DQ839239). By comparison of their deduced amino acid sequences with those of S1-to S36-alleles of Oriental pear, it can be seen that both the two new S-alleles had their conserved regions C1 and C2, but their hypervariable regions (HV) were quite different from those of the others. S37 showed a higher similarity (96%) to S38 in the amino acid sequences deduced from them, whereas both of them displayed the highest similarity (98%) to S15 and the lowest (63%) to S32. The two S-alleles had introns of 786 bp and 723 bp, respectively, similar in size to that of S15 (777 bp). Finally, the S-genotypes of 'Jinxiang' and 'Esu' were unambiguously determined as S34S37 and S15S38, respectively.