杏自交不亲和相关S-RNase基因的克隆及表达

摘要: 从巴旦水杏(Prunus aremeniaca L. cv. Badanshui)、红玉杏(P. aremeniaca L. cv. Hongyu)和凯特杏(P. aremeniaca L. cv.Katy)3个品种中通过RT-PCR和RACE克隆出3个S-RNase片段， 分别被定名为PA1、PA2、PA3，片段大小分别为576、601和591 bp。3个基因的氨基酸的相似性达80.6%。将这3个基因与蔷薇科中其它树种的S- RNase比较表明，蔷薇科S-RNase的氨基酸序列变异很大，亚科内的相似性高于亚科间的，在所编码的187个氨基酸中只有14个氨基酸残基是完全保守的，高度变异（RHV）区PA1有H、M两个残基和PA3有N、S、A　3个残基不同于其它的S-RNase，这表明不同的残基可能起着S-等位基因专一性识别的作用。从蔷薇科、茄科及一些S-like RNase 的系统树分析可看出，苹果和梨分属于苹果亚科类，樱桃、扁桃和杏分属于李亚科类，同时也证明了实验中所得到的3个氨基酸序列是S-RNase的一个分支而不是S-like RNase的分支。 Northern 杂交分析表明凯特杏表达的PA3只在花柱中专一表达，在根、茎和叶中未表达，杂交斑的分子量为0.9 kb。序列分析及在基因库中搜索结果证明，本研究所得到的3个基因是S-RNase表达的基因。

Cloning and Expression of Self-incompatibility Related S-RNase Gene in Apricot

Abstract:Three cDNAs named PA1, PA2 and PA3 were isolated from self-incompatibility cultivars of Badanshui, Hongyu and self-compatibility Katy apricot(Prunus aremeniaca ). They encode 576 , 601 and 591 bp，respectively.There was 80.6% similarity among their amino acid sequences. The comparison of amino acid sequences of Rosaceae S-RNase showed highly divergent, and intra-subfamilial similaritiy was higher than that of inter-subfamilial one. Fourteen sites were perfectly conserved among encoded 187 amino acid residues , and in hyperaviable region(RHV) two amino acid residues (H, M) in PA1 and three amino acid residues(N, S, A) in PA3 were different from other S-RNase, which indicated the different amino acid residues might play a role of S-allele gene special recognition. From the phylogentic tree about Rosaceae, Solanaceous and some S-like RNase, apple and pear belong to Maloideae, but cherry, almond and apricot belong to Amygdaloideae, and three sequences were identified to be homology to S-RNase not to S-like RNase from other families. Northern blotting analyses indicated that PA3 was expressed predominatly in pistils of Kate apricot, which molecular weight was 0.9 kb, but not expressed in root, stem and leaf of Katy apricot. According to the sequence analyses and blast in GenBank, the result showed the obtained three genes were expression genes of S-RNase.