title: Geographic distribution of cryptic species of Plasmopara viticola causing downy mildew on wild and cultivated grape in eastern North America.
abstract: The putative center of origin of Plasmopara viticola, the causal agent of grape downy mildew, is eastern North America, where it has been described on several members of the family Vitaceae (e.g., Vitis spp., Parthenocissus spp., and Ampelopsis spp.). We have completed the first large-scale sampling of P. viticola isolates across a range of wild and cultivated host species distributed throughout the above region. Sequencing results of four partial genes indicated the presence of a new P. viticola species on Vitis vulpina in Virginia, adding to the four cryptic species of P. viticola recently recorded. The phylogenetic analysis also indicated that the P. viticola species found on Parthenocissus quinquefolia in North America is identical to Plasmopara muralis in Europe. The geographic distribution and host range of five pathogen species was determined through analysis of the internal transcribed spacer polymorphism of 896 isolates of P. viticola. Among three P. viticola species found on cultivated grape, one was restricted to Vitis interspecific hybrids within the northern part of eastern North America. A second species was recovered from V. vinifera and V. labrusca, and was distributed across most of the sampled region. A third species, although less abundant, was distributed across a larger geographical range, including the southern part of eastern North America. P. viticola clade aestivalis predominated (83% of isolates) in vineyards of the European winegrape V. vinifera within the sampled area, indicating that a single pathogen species may represent the primary threat to the European host species within eastern North America.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Rouxel
authors.forename: Pere
authors.initials: P
authors.lastname: Mestre
authors.forename: Anton
authors.initials: A
authors.lastname: Baudoin
authors.forename: Odile
authors.initials: O
authors.lastname: Carisse
authors.forename: Laurent
authors.initials: L
authors.lastname: Delière
authors.forename: Michael A
authors.initials: MA
authors.lastname: Ellis
authors.forename: David
authors.initials: D
authors.lastname: Gadoury
authors.forename: Jiang
authors.initials: J
authors.lastname: Lu
authors.forename: Mizuho
authors.initials: M
authors.lastname: Nita
authors.forename: Sylvie
authors.initials: S
authors.lastname: Richard-Cervera
authors.forename: Annemiek
authors.initials: A
authors.lastname: Schilder
authors.forename: Alice
authors.initials: A
authors.lastname: Wise
authors.forename: François
authors.initials: F
authors.lastname: Delmotte
mesh_terms: D001061:Appalachian Region; D001483:Base Sequence; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D005431:Florida; D005843:Geography; D006114:Great Lakes Region; D058507:Host Specificity; D008969:Molecular Sequence Data; D044742:Peronospora / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D010802:Phylogeny; D010935:Plant Diseases / Q000469:parasitology*; D018515:Plant Leaves / Q000469:parasitology; D011792:Quebec; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D027843:Vitis / Q000469:parasitology*
chemical_list: D021903:DNA, Ribosomal Spacer
keywords: plant pathogen