三浅裂野牵牛NBS类抗病基因同源序列的克隆与分析

NBS类植物抗病基因保守结构域的克隆为利用简并引物扩增抗病基因同源序列提供了可能.根据抗病基因Gro1-4、Gpa2、N等的P-loop和GLPL保守结构域设计简并引物,分离甘薯近缘野生种三浅裂野牵牛NBS类型抗病基因同源序列,共获得6条相关序列,核苷酸序列的相似性为48%~97%,推测氨基酸序列的相似性在25.2%~95.1%之间.系统进化分析表明,6条三浅裂野牵牛RGA序列可分为2个不同的类群:TIR-NBS和non-TIR-NBS.三浅裂野牵牛RGA序列与源自甘薯的RGA序列有很高的相似性,这在一定程度上反映了三浅裂野牵牛与甘薯之间的亲缘关系.分离的6条RGA序列分别命名为ItRGA1~ItRGA6,GenBank登录号分别为DQ849027~DQ849032.

Cloning and Analysis of NBS Class Resistance Gene Analogues in Ipomoea trifida

Most plant disease-resistance genes(R-genes)isolated so far encode proteins with nucleotide binding site(NBS)domain which belong to a superfamily.NBS domains related to R-genes show a highly conserved backbone of amino acid motif,which makes it possible to isolate resistance gene analogues(RGAs)by degenerate primers.Degenerate primers based on conserved motif(P-loop and GLPL)of NBS domain from R-genes were used to isolate RGAs from genomic DNA of Ipomoea trifida,a close wild relative of sweet potato,six I.trifida RGA sequences were obtained.Sequence similarity among the 6 RGA nucleotide sequences ranged from 48% to 97%,while the deduced amino acid sequences similarity from the 6 RGAs ranged from 25.2% to 95.1%.The phylogenetic analyses for RGA nucleotide sequences and the deduced amino acids showed that RGAs from I.trifida could be classified into two distinct groups,TIR(toll and interleukin receptor-1)-NBS and nonTIR-NBS.The high similarity between I.trifida RGAs and sweet potato RGAs in GenBank database indicates an ancestral relationship.The I.trifida RGAs have been designated ItRGA1~ItRGA6 and deposited in the GenBank database under Accession Nos.DQ849027~DQ849032,respectively.