Abstract: 【Objective】In this study, resistance gene homology fragments from wheat were isolated using homology-based method. 【Method】Two pairs of primers were designed according to the amino acid conserved regions NBS-LRR of the cloned plant disease resistance genes, and the reverse transcription-polymerase chain reaction (RT-PCR) was used.【Result】Three open-reading NBS resistance gene analogues (RGAs) have been obtained. They were named as PS13-1, PS13-2, and S2A2 respectively from the RNA of TcLr35 carrying the Lr35 gene conferring resistance against wheat leaf rust by a reverse transcription-polymerase chain reaction (RT-PCR). The nucleotide sequences of the three RGAs were 239bp, 289bp and 539bp encoding 78, 84 and 177 amino acids respectively. Homology research showed that the nucleotides of PS13-1 and PS13-2 were 91% identical to wheat powdery mildew resistance gene PM3b, and the nucleotide of S2A2 was 91% identical to the sequence from the mRNA of barley. BLASTp analysis indicated that three RGAs contained the conserved motifs of NB-ARC (such as P-loop, kinase2, kinase3a and transmembrance domain). Northern hybridization showed that the RGAs expression was not induced by Puccinia recondite inoculation suggesting that the gene be a constitutive gene with low abundance in wheat. 【Conclusion】In this study, three resistance homology sequence were obtained in TcLr35, which provide the shortcut for the cloning of wheat leaf rust resistance genes.

Key words: Wheat leaf rust resistance gene, NBS-LRR, Homology sequence