海岛棉NBS类型抗病基因类似物的起源、多样性及进化

Origin,Diversity and Evolution of NBS-type Disease-resistance Gene Analogues in Sea-island Cotton (Gossypium barbadense L.)

利用已克隆植物的R基因NBS序列中保守模体合成简并引物 ,以海岛棉品系Pima 90 (Gossypiumbarba dense)基因组DNA为模板进行PCR扩增 ,通过T A克隆、测序和序列比较分析共得到 31条RGAs ,其中 1 9条具有连续的ORF。利用海岛棉的 31条RGAs与GenBank中陆地棉种质系M 2 4 9(Gossypiumhirsutum)的RGAs进行了比较分析 ,RGAs可分为两大类 :其中第Ⅰ类全部为陆地棉的RGAs;第Ⅱ类分别包括了陆地棉和海岛棉的RGAs。同时对海岛棉RGAs的核苷酸和氨基酸序列进行系统发育树分析 ,表明海岛棉RGAs可分为TIR(DrosophilaTollorhumaninter leukinreceptor like)和non TIR两类 ,与前人所报道的R基因进化一致。对 1 9条具有连续ORF的RGAs进行了结构分析 ,结果表明它们包括P loop、Kin 2、“PLAL”及Meyers等所定义的RNBS A、B、C 3个模体。结果表明 。

The majority of plant disease resistance genes (R genes) isolated encodes a predicted nucleotide binding site (NBS) domain.The NBS sequences can be divided into two major groups.GroupⅠ of NBS domains contains TIR ( Drosophala Toll or human interleukin receptor like ) and groupⅡ does not.The two groups are all distributed in dicot species.NBS domains related to R genes show a highly conserved backbone of amino acid motifs,which makes it possible to isolate resistance gene analogues (RGAs) by PCR with degenerate primers.Multiple combinations of primers designed from two conserved motifs in the NBS regions of R genes of various plants were used to amplify genomic DNA of sea island cotton,var.Pima 90 ( Gossypium barbadense ),the desired bands were purified from the gel,and then cloned by T/A cloning.After sequenced and analyzed by alignment,31 RGAs were isolated.Among the RGAs,nineteen were uninterrupted open reading frames (ORFs).We have multialigned the 31 RGAs and 34 RGAs of ( Gossypium hirsutum ) germline M 249 by searching in GenBank,they were divided into two classes.ClassⅠ included only upland cotton RGAs,class Ⅱ include all upland cotton and sea island cotton RGAs.Two distinct groups,TIR type and non TIR type,were classified by phylogenetic analysis in sea island cotton.The analysis of the 19 ORFs structures suggested that they contain the motifs such as P loop,Kin 2,“PLAL” and RNBS A,B,C,as defined by Meyers.These indicate that NBS type disease resistance gene analogues in sea island cotton have the common origin and evolution with the other plants.