2种根结线虫Cg-1及其同源基因的克隆和序列分析

Root-knot nematode Cg-1 and its homologous genes cloning and sequences analysis

采用同源克隆的方法,首次从能克服Mi-1抗性的象耳豆根结线虫(Meloidogyne enterolobii)中克隆了Cg-1同源基因,同时克隆了一个爪哇根结线虫无毒种群的Cg-1及其同源基因。基因序列比较结果显示,象耳豆根结线虫中不存在Cg-1基因,即象耳豆根结线虫中只具有不包含CAATGA片段的Cg-1同源序列,进一步表明Cg-1可能是一个无毒基因。对Cg-1基因序列分析的结果表明,Cg-1基因可能是通过其第三个开放阅读框(ORF)编码的多肽或结构性mRNA或两者共同行使生物学功能。

Cg-1,with 8 homologous genes,from Meloidogyne javanica is a candidate avirulence gene corresponding to tomato resistance gene Mi-1.Comparing with its homologs,Cg-1 contains a CAATGA fragment insertion.In this study,Cg-1 homologous clones from Meloidogyne enterolobii,a root-knot nematode that is able to overcome tomato Mi-1 resistance,were firstly cloned.Meanwhile,Cg-1 and its homologous clones of an M.javanica avirulent strain in our laboratory were cloned.Comparison of Cg-1 and these homologous clones from M.enterolobii and M.javanica strains showed that Cg-1 gene was inexistent in M.enterolobii that is there were only Cg-1 homologous genes which did not contain CAATGA existing in M.enterolobii.This result further indicated that Cg-1 may be an avirulence gene.Sequence analysis of Cg-1 gene predicts that the third open reading frame（ORF） encoding peptide and its structural mRNA,or both exercise biological function of Cg-1.