Abstract: In this research，a full-length cDNA sequence of Mlo gene，named RmMlo（GenBank accession No. JF310747）was obtained from leaves of Rosa multiflora by RT-PCR and RACE. Sequence analysis indicated that RmMlo was 1 993 bp in full length containing a 5′-untranslated region（5′-UTR）of 49 bp，a 3′-UTR of 243 bp，and an opening reading frame（ORF）of 1 700 bp encoding 567 amino acids. Subsequently，amino acid sequence analysis revealed that RmMlo had two conserved MLO motifs in the protein C-terminal. Sequence alignment and phylogenetic analysis showed that RmMlo shared more than 90% homology with Mlo from Arabidopsis thaliana and other dicotyledon. Finally，semiquantitative RT-PCR analysis indicated that RmMlo showed the highest expression abundance in infected leaves and no expression in root，which was different from the expression pattern of AtMlo.

Key words: Rosa multiflora, rose, powdery mildew, Mlo, clone, tissue-specific expression