Cloning and Characterization of Disease Resistance Protein RPM1 Genes against Powdery Mildew in Wheat Line N9134

Powdery mildew (Blumeria graminis f. sp. tritici) is one of the most devastating wheat diseases. The wheat line N9134 contains PmAS846 that was transferred to N9134 from wild emmer wheat, and is still one of the most effective resistance genes in China. A full-length wheat RPM] gene was obtained by rapid amplification of cDNA ends (RACE) based on the up-regulated probe sequence from differentially expressed transcripts during the N9134 and powdery mildew interaction. The gene was named TaRPM1, and the open reading frame (ORF) is 2721 nucleotides and encodes a polypeptide of 907 amino acids with a predicted isoelectric point of 4.86. Phylogenetic analysis revealed that TaRPM1 was highly homologous on both Aegilops tauschii and Triticum urartu at both the nucleotide and protein level. Using real-time quantitative PCR, the TaRPM1 gene expression level in wheat leaves was found to be sharply up-regulated, while the transcript level was lowly induced in the root and stem. Under the powdery mildew treatment, the transcription profile of TaRPM1 was very strongly expressed at 48 hour post inoculation (hpi), which increased again to 96 hpi and reaching a high level at 120 hpi. Based on sequence similarities and positions, we inferred that the TaRPM1 gene was on wheat chromosome 3D. These results suggested that TaRPM1 plays an important role in the mechanism of innate immunity to infection by the powdery mildew pathogen.