辣椒抗病基因同源序列的克隆与分析

 【目的】利用同源序列法分离辣椒抗病基因同源序列。【方法】根据已知植物抗病基因的NBS-LRR保守结构域设计简并引物，以辣椒品系PR205基因组DNA为模板对抗病基因同源序列进行扩增。【结果】获得了25个抗病基因同源序列（resistance gene analogs，RGAs），聚类分析将其分为7个不同的类别。由其核酸序列推导的氨基酸序列与Mi-1.2、prf、Hero、I2C-1、RPM1基因相应区域的同源性为27.4%～98.2%。其中RGA-p20与Mi-1.2 基因的核苷酸和氨基酸序列相似性均达到99%，确认RGA-p20为抗根结线虫基因的一部分，即辣椒中也含有与Mi基因同源的根结线虫抗性基因。【结论】本研究在辣椒品系PR205中获得了抗病基因同源序列，为辣椒抗病基因的克隆奠定了基础。

Cloning and Analysis of Resistance Gene Analogs from Pepper (Capsicum annuum L.)

【Objective】 Resistance gene analogs are isolated from pepper using homology-based method. 【Method】The genomic DNA of pepper (Capsium annuum L.) line PR205 was amplified using degenerated primers which were designed based on the conserved regions of Nucleotide Binding Site (NBS)-Leucine Rich Repeat (LRR) domain from previously reported plant resistance genes. 【Result】Twenty-five Resistance Gene Analogs (RGAs) have been obtained. These RGAs were classified into seven distinct groups by phylogenetic analysis. Putative amino acid sequences deduced from these 25 RGAs shared 27.4%-98.2% identity with the resistance genes of Mi-1.2, prf, Hero, I2C-1 and RPM1. RGA-p20 showed an extreme sequence identity (99%) with Mi-1.2 at nucleotide/amino acid levels. It suggests that there is a root knot nematode resistance gene which is homology with Mi gene in pepper of PR205 and RGA-p20 is one part of this resistance gene.【Conclusion】In this study, twenty-five RGAs were obtained in pepper line PR205, which laid a promsing foundation for cloning of resistance genes from pepper.