甘薯中NBS-LRR类抗病基因同源序列的克隆及序列分析

根据已知的NBS-LRR类抗病基因蛋白质的保守序列设计简并引物,用以扩增甘薯基因组中的抗病基因同源序列,获得一条大小约500 bp的扩增片段,克隆测序后得到20个NBS-LRR类抗病基因同源片段RGAS。其推导的氨基酸序列均具有P-loop、Kinase-2a和Kinase-3a及GLPL区等几个保守区,并且可分为TIR-NBS-LRR和non-TIR-NBS-LRR两个亚类。其中10个TIR亚类RGAS与已克隆的N、L6、M等抗病基因相应区段的氨基酸序列的同源性为21%-44%,而10个non-TIR亚类RGAS与已克隆的Prf、RPM1、RPS2等抗病基因相应区段的氨基酸序列的同源性为15%-46%。这些抗病基因同源片段(RGA)可做为分子标记筛选甘薯的抗病候选基因。

Cloning and Analysis of NBS-LRR Type Resistance Gene Analogs in Sweet Potato (Ipomoea batatas)

The degenerate primers were designed based on the conserved NBS-LRR motifs among the known disease-resistance genes.The primers were used to amplify the disease-resistance gene analogues(RGAs) in Sweet Potato(Ipomoea batatas).A PCRproduct about 500 by was obtained.After cloning and sequencing,20 NBS-LRR type RGAs in sweet potato were detected.The deduced amino acid sequences of the DNA fragments contained the conserved motifs of NBS-LRR type RGAs,such as P-loop,Kinase 2a,kinase 3a and GLPL domains.These 20 RGAs could be sorted into two distinct types,TIR-NBS-LRR type and non-TIR-NBS-LRR type.When the sequences of 10 TIR type RGAs were compared with known resistance gene (N,L6,M etc.)sequences,the percentage of aminoacid identity as ranged from 21%~44%,While the other 10 non-TIR type RGAs had 15%~46% homologous compared with known resistance gene(Prf,RPM1,R PS2 etc.).The RGAs may further be used as molecular marker for screening of candidate disease-resistance genes in sweet potato.