1National Key Laboratory of Agromicrobiology, Huazhong Agricultural University, Wuhan, Hubei 430070, People’s Republic of China
2Department of Biology and Plant Protection, University of Udine, Italy
3The Key Laboratory of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan, Hubei 430070, People’s Republic of China
4Greenhouse and Processing Crops Research Centre, Agriculture and Agri-Food Canada (AAFC), Harrow, Ontario, N0R 1G0, Canada
Peach and nectarine trees exhibiting typical peach X disease symptoms including leaf yellowing, necrosis, and vein yellowing were observed during a survey in commercial orchards in Essex (Southern Ontario, Canada). A total of 1,828 plants were inspected and 2.8% of them resulted symptomatic. Specific nested-PCR assays on 16S rDNA allow phytoplasma identification on samples from 51 symptomatic trees. Twelve samples from peach and nectarine were selected for RFLP and sequence analyses; results indicated the presence in eleven samples of CX-related phytoplasmas belonging to 16SrIII-A subgroup, while in one sample a profile indicating possible mixed infection or interoperon heterogeneity was observed. Cloning of the amplicons confirmed the presence of two RFLP differentiable sequences. Sequence analyses of the ribosomal protein gene from the same sample indicate that it clusters with phytoplasmas in ribosomal protein subgroup rpIII-A.
peach X disease, nested-PCR, RFLP, phylogenetic analysis, similarity coefficient
