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 6RGAs 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.
NETL
NSTL
万方数据
维普
