马铃薯抗晚疫病基因Rpi-blb2是来源于马铃薯野生种Solanum bulbocastanum中的一个具有广谱抗性的NBS-LRR类抗病基因。文章用PCR的方法从20个高抗晚疫病的马铃薯栽培种和20个高感晚疫病的马铃薯栽培种以及7个马铃薯野生种中克隆了Rpi-blb2基因的 LRR区段。采用生物信息学方法对这些序列的相似性、多态性位点、核酸多样性指数等参数进行了分析, 发现Rpi-blb2 的LRR区域在核酸水平上变异程度很高, 而且存在多处热点突变位点; 通过对该区域的Ka/Ks值进行估算, 发现Rpi-blb2 的LRR区域总体上受到纯化选择, 功能保守, 但是LRR区域的不同部位所受到的选择压力却不尽相同。同时, 从核酸水平来看, Rpi-blb2 基因的LRR区域在马铃薯栽培种和马铃薯野生种之间没有发现明显的分化。
Rpi-blb2, which is originally derived from Solanum bulbocastanum, is a broad-spectrum potato late blight resistance gene and belongs to the NBS-LRR family. Here, the LRR homologues of Rpi-blb2 were cloned with PCR method from 40 potato cultivars (including 20 resistant potato cultivars and 20 susceptible ones) and 7 wild potato popula-tions. Then, the similarities of the sequences, polymorphic (segregating) sites, and nucleotide diversities were estimated by bioinformatic methods. The results showed that high nucleotide polymorphism and some hot-spot mutations existed in the LRR region of Rpi-blb2. The test of Ka/Ks ratio showed that the function of LRR was conserved because of the purifying selection, although different positions of the Rpi-blb2 LRR region were under different selection pressures. Moreover, the LRR region of Rpi-blb2 had no clear differentiation between the cultivated and wild potatoes.
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