棉花多抗品种中植棉KV-1抗病基因同源序列的克隆与分析

 许多抗病基因都具有核苷酸结合位点（NBS）和富亮氨酸重复区（LRR）。根据已知的NBS-LRR类抗病基因的保守序列，分别设计一对简并引物和一对特异引物，用以扩增棉花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10条NBS-LRR类RGAs。推导的氨基酸均具有抗病基因的P-loop（kinase-1a）、kinase-2、kinase-3a及GLPL区。同源性比较发现，其中1条属于TIR-NBS LRR类，其余9条属于non-TIR-NBS-LRR类。1条TIR-NBS-LRR类RGAs与已克隆的N、L6、M等抗病基因的同源性为51%~60%，9条non-TIR-NBS-LRR类RGAs与已克隆的RPS5、RPR1、Xa1等抗病基因的同源性为51%~60%。这些抗病基因同源序列（RGAs）可作为分子标记筛选棉花的抗病候选基因。

Isolation, Characterization and Phylogenetic Analysis of the Resistance Gene Analogues (RGAs) in Upland Cotton (Gossypium hirsutum L.) Zhongzhimian KV-1

Most of known plant disease-resistance genes are featured with a nucleotide-binding site (NBS) and leucine-rich repeats (LRR)．A pair of degenerate primers and a pair of specific primer 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 upland cotton (Gossypium hirsutum L.)．A PCR product about 500 bp was obtained．After cloning and sequences of the DNA fragments,10 NBS-LRR type RGAs were obtained．The deduced amino acid sequences of the DNA fragments contained the conserved motifs of NBS-LRR type RGAs,such as P-loop（kinase-1a）,kinase-2,kinase-3a and GLPL domains．One of the RGAs is belonged to TIR-NBS-LRR type and the other nine are belonged to non-TIR-NBS-LRR type．When the TIR-NBS-LRR type RGA was compared with known disease-resistance gene such as N、L6、M,the percentage of amino acid homology ranged from 51% to 60%,while the other nine non-TIR-NBS-LRR type RGAs had 51%～60% homologous compared with known resistance gene such as RPS5、RPR1、Xa1 and so on．These RGAs may be further used as molecular marker for screening of candidate disease-resistance gene in cotton.