Cloning and Characterization of a NBS Resistance Gene Homology cDNA Sequence from Wheat

Resistance gene homology sequence from wheat was isolated by using homology-based method.A pair of degenerated primer was designed according to the nucleotide binding site conserved domains of the cloned plant disease resistance(R) genes.RT-PCR and RACE were used to obtain the full length sequence of the disease resistance homology gene in the near isogenic lines TcLr19.One open-reading NBS class of resistance gene analogs(RGAs) named S11A11 was obtained,which was 2923bp in length and encoded 878 amino acids.Bioinformatics analysis showed the deduced amino acids of S11A11 protein consisted of a NB-ARC conserved domain and many leucine-rich repeats(LRR) domains.The phylogenetic tree analysis indicated a considerable identity of the protein encoded by S11A11 with that of wheat leaf rust resistance gene Lr1,but a lower similarity with Lr10.The S11A11 gene appeared not to be induced by Puccinia triticina and was a constitutive gene with low abundance in wheat leaf tissue by semi-quantitative RT-PCR.The resistance homology sequence was successfully obtained in TcLr19,which provides the shortcut for cloning of wheat leaf rust resistance gene.