水稻基因组中抗病基因正选择方式及基因转换的研究

Patterns of Positive Selection and Gene Conversion in the Complete Disease Resistance Genes of Rice

【目的】了解正选择压力和基因转换对水稻全基因组中NBS-LRR抗病基因家族进化的影响及二者之间的相互关系。【方法】对水稻全基因组中的NBS-LRR基因进行鉴别与分类,利用PAML和GENECONV程序分别进行正选择替代和基因转换分析。【结果】在19个组(包含89个NBS-LRR基因)中检测出了显著的正选择替换位点,且约有60%正选择位点位于LRR区域;56个基因至少参与了1次基因转换事件。同时,基因转换、正选择以及基因簇之间存在明显的相关性。在84%的参与基因转换的基因中都能检测出正选择位点,且至少有84%的发生基因转换或正选择的基因都位于基因簇中。【结论】水稻基因组中的NBS-LRR基因之间,存在着频繁的正选择替代和基因转换。

【Objective】 In order to understand the evolution of disease resistance in rice genome,we performed a genome-wide analysis of positive selection and gene conversion in members of the nucleotide binding site NBS-LRR gene family of Oryza sativa L.var.Nipponbare.【Method】The positive selection sites was calculated with the computer program Codeml from PAML.Sequence exchange was investigated by the program GENECONV.【Result】Analyses were possible for 172 of 457 NBS-LRR genes in the genome,and the analyses uncovered substantial evidence of positive selection and gene conversion.Sites under positive selection were detected and identified for 19 sequence groups representing 89 NBS-LRR genes and approximate 60% of positively selection sites were located in the LRRs region.At least one gene conversion event was detected in 56 NBS-LRR genes.Positively selection sites were identified in 84% of genes which were detected in a gene conversion event.Most of the genes detected in positive selection or gene conversion were resided in gene clusters.【Conclusion】Frequent positive selection and gene conversion evens were detected among NBS-LRR genes in rice genome.