梨20个品种S基因型的鉴定及新S-RNases基因克隆

 为了鉴定我国梨品种和一些野生类型个体的S基因型，应用S-RNase特异PCR扩增、克隆和测序，对其S-RNases基因核苷酸序列进行分析，鉴定了20个梨品种和野生类型个体的S基因型。起源于我国的'奥连'(S_pS₃₂)、'吊蛋'(S_dS_e)、'沙疙瘩'（S₃₆S_d）品种和杏叶梨的一个类型（S₂₂S_c）个体中存在西洋梨的S-RNase基因，证明S-RNase基因分化是在东方梨种群和西方梨种群的各个种形成之前。在秋子梨的'麦梨'、'内蒙古山梨'中发现了2个新S-RNases基因，命名为S₄₀-、S₄₁-RNase（DQ903313、DQ988687）。S₄₀-和S₄₁-RNase基因推导的部分氨基酸序列分别与苹果属S₁₁-和S₆-RNase的同源性为100%和94.4%，这表明S-RNase的存在可能在梨属和苹果属形成之前。

Identification of 20 S-genotypes and Cloning Novel S-RNases in Pyrus

To identify S-genotypes of pear cultivars or a few types of wild species native to China，S-RNase specific PCRs were used. After cloning and sequencing of PCR products , the S-genotypes of 20 pear cultivars or wild species individuals were determined. Subsequent sequence analysis showed that 'Aolian' (S_pS₃₂) from Pyrus. sinkiangensis Yü, 'Diaodan'(S_dS_e) from P. phaeocarpa Rehd, 'Shageda'(S₃₆S_d) from P. xerophila Yü and one type of Xingyeli(S₂₂S_c) originated from China shared some S-RNases with species from P. communis , which provided with evidence that S-RNase alleles occurred before the divergence of oriental and occidental pear. Two novel S-RNases were also discovered in 'Maili' and 'Neimenggushanli' in P. ussuriensis, and deposited as S40-, S41-RNase under the accession numbers of DQ903313 and DQ988687, respectively, whose deduced amino acid sequences showed high similarities to S₁₁-RNase(100% ) and S₆-RNase (94.4%) in Malus, respectively. The high similar score between S-RNase in Pyrus and Malus indicated that S-RNase existence predated the speciation between Pyrus and Malus.