title: Classification of phytoplasma strains in the elm yellows group (16SrV) and proposal of 'Candidatus Phytoplasma ulmi' for the phytoplasma associated with elm yellows.
abstract: Elm yellows group (16SrV) phytoplasmas, which are associated with devastating diseases in elm, grapevine, blackberry, cherry, peach and several other plant species in America, Europe and Asia, represent one of the most diverse phytoplasma clusters. On the basis of phylogenetic analysis of 16S rDNA sequences, elm yellows group phytoplasmas form a discrete subclade within the phytoplasma clade. Three phylogenetic parameters, namely 16S rRNA, ribosomal protein and secY genes, have been evaluated for their usefulness in differentiating elm yellows group phytoplasmas. RFLP analysis of 16S rRNA sequences differentiated the elm yellows group phytoplasmas into five subgroups. Twelve RFLP subgroups were differentiated on the basis of ribosomal protein and 13 were differentiated using secY gene sequences. Phylogenetic analysis of the ribosomal protein genes and secY gene alone or in combination indicated that the subgroups constitute 12 genetically distinct lineages, each of which appears to have evolved under different ecological constraints such as specific vector or plant hosts. On the basis of unique DNA and biological properties, it is proposed that the elm yellows phytoplasma EY1(T) represents a novel taxon, 'Candidatus Phytoplasma ulmi'.
authors.affiliation: USDA-ARS Molecular Plant Pathology Laboratory, Beltsville, MD 20705, USA.
authors.forename: Ing-Ming
authors.initials: IM
authors.lastname: Lee
authors.affiliation: Dipartimento di Biologia Applicata alla Difesa delle Piante, University of Udine, 33100 Udine, Italy.|USDA-ARS Molecular Plant Pathology Laboratory, Beltsville, MD 20705, USA.
authors.forename: Marta
authors.initials: M
authors.lastname: Martini
authors.affiliation: Dipartimento di Biologia, Difesa e Biotecnologie Agro-Forestali, University of Basilicata, 85100 Potenza, Italy.
authors.forename: Carmine
authors.initials: C
authors.lastname: Marcone
authors.affiliation: Institute of Animal and Plant Quarantine, Beijing 10029, PR China.|USDA-ARS Molecular Plant Pathology Laboratory, Beltsville, MD 20705, USA.
authors.forename: Shifang F
authors.initials: SF
authors.lastname: Zhu
mesh_terms: D000129:Acholeplasmataceae / Q000145:classification* / Q000302:isolation & purification / Q000472:pathogenicity; D001483:Base Sequence; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D034403:Ulmus / Q000382:microbiology*
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S