Using electronic cloning method,the putative disease resistance protein RGA4 and the homologue of the potato Rpi-blb1protein were obtained from tomato’s protein sequences database in NCBI by protein-blast when the sequence of late blight resistant protein Rpi-blb1 from potato was used as query sequence,then,they were compared in gene mapping,gene structure,modify,secondary structure,topological structure and electronic gene expression pro-file,etc,for proving their evolutionary relationship.The result showed that tomato RGA4 protein (XP_004245923.1) was composed of 988 amino acid residues with NB-ARC and LRR8 conserved domain,the corresponding cDNA se-quence (XM-004245875.1)was located on SL2.40 region in the chromosome 8,with genomic DNA length 4 089 bp, the alignment region in chromosome 8 between 57228847 - 57232935 bp,and composed of two exons and one intron.The tomato RGA4 protein was an unstable globular secretory protein without transmembrane structure.To-mato RGA4 protein was regarded as an orthologous of potato Rpi-blb1 protein because they were similar in secondary structure composition,gene sequence composition,gene mapping,etc,but their minor differences in gene evolution and composition could result in different functions.This study would provide theory for cloning late blight resistant gene and its utilization in tomato breeding of disease resistance.%为获得番茄抗晚疫病广谱性基因信息,采用同源电子克隆法,基于番茄蛋白序列数据库,以马铃薯晚疫病广谱抗性蛋白 Rpi-blb1为种子序列,获得番茄疾病抗性蛋白 RGA4,并进行基因电子定位和基因结构、模体、二级结构、基因进化及基因电子表达等分析,以证明两者的进化关系.结果表明：番茄 RGA4蛋白(XP_004245923．1)序列具有 NB-ARC 和 LRR8两个保守结构域,定位于第8条染色体 SL2．40区间,相应基因位于8号染色体序列的57228847－57232935 bp 区间,长度为4089 bp,由2个外显子和1个内含子组成,编码988个氨基酸序列,该蛋白为不稳定分泌球形蛋白；番茄 RGA4蛋白和马铃薯 Rpi-blb1蛋白在二级结构分布、基因序列组成、基因定位等方面相似性较高,可确定两者为垂直同源关系,但在基因进化和模体组成方面存在差异,可能导致两者功能上的不同.研究结果可为番茄晚疫病广谱抗性基因克隆及其利用提供理论依据.
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