Genotyping Points to Divergent Evolution of ‘CandidatusPhytoplasma asteris’ Strains Causing North American Grapevine Yellows and Strains Causing Aster Yellows

Abstract

Grapevine yellows diseases occur in cultivated grapevine (Vitis vinifera L.) on several continents, where the diseases are known by different names depending upon the identities of the causal phytoplasmas. In this study, phytoplasma strains associated with grapevine yellows disease (North American grapevine yellows [NAGY]) in vineyards of Pennsylvania were characterized as belonging to 16S ribosomal RNA (rRNA) gene restriction fragment length polymorphism group 16SrI (aster yellows phytoplasma group), subgroup 16SrI-B (I-B), and variant subgroup I-B*. The strains (NAGYI strains) were subjected to genotyping based on analyses of 16S rRNA and secY genes, and to in silico three-dimensional modeling of the SecY protein. Although the NAGYI strains are closely related to aster yellows (AY) phytoplasma strains and are classified like AY strains in subgroup I-B or in variant subgroup I-B*, the results from genotyping and protein modeling may signal ongoing evolutionary divergence of NAGYI strains from related strains in subgroup 16SrI-B.

When a Palearctic bacterium meets a Nearctic insect vector: Genetic and ecological insights into the emergence of the grapevine Flavescence dorée epidemics in Europe

“…Phytoplasma asteris' and 'Ca. Phytoplasma pruni' [33][34][35], while 16SrV-C phytoplasmas were detected in wild plants such as Apocynum cannabinum in New York and Parthenocissus quinquefolia in Florida [24,36,37]. We previously demonstrated by MLSA that 16SrV-C and V-D phytoplasmas detected in European alders, clematis and grapevine had a common phylogenetic origin [23,24].…”

Jikradia olitoria([Hemiptera]:[Cicadellidae]) Transmits the Sequevar NAGYIIIβ Phytoplasma Strain Associated with North American Grapevine Yellows in Artificial Feeding Assays

“…The phytoplasmas recovered in the artificial diet were identified as NAGYIIIβ, a common phytoplasma sequevar found in NAGY-affected, cultivated grapevines in the eastern United States (Davis et al 2015). This is the most compelling evidence yet of a competent NAGY vector, even though it does not rule out the fact that other leafhoppers could be potential vectors of this sequevar, the closely related NAGYIIIα sequevar, or the less commonly found 16SrI (aster yellows group) phytoplasma (Davis et al 1998, Davis et al 2018).…”

“…Although the disease was observed in Virginia since the 1980s, the ecology and epidemiology of NAGY remain poorly understood. Although considerable progress has been made in the characterization of the causal pathogens of NAGY (e.g., Davis et al 2015, 2018) and the detection of alternative hosts (our unpublished data), the identification of the insect vector species is lacking.…”

“…Phytoplasma pruni-related’ strains. The second NAGY phytoplasma, classified in the rRNA RFLP 16SrI aster yellows group, was recently assigned to 16SrI subgroup I-B and variant subgroup I-B* on the basis of genotypic analyses of the 16S rRNA and secY genes, complemented with 3D, in silico modeling of the SecY protein (Davis et al 2018).…”

Review: Genomics of interactions between phytoplasmas, host plants and vector insects

“…Entre ellos se incluyen el gen del factor de elongación tufB (Marcone et al, 2000;Malembic-Maher et al, 2011), proteínas ribosomales rp (Martini et al, 2007), el chaperon molecular groEl (Mitrović et al, 2011a), la proteína de la maquinaria de secreción secY (Lee et al, 2006) y el gen secA (Hodgetts et al, 2008;Bekele et al, 2011), entre otros. Por lo general, las relaciones filogenéticas que se predicen con otros genes son similares a las estimadas con 16SrRNA (Mitrović 2011a, b;Lee et al, 2004, Martini et al 2007, Hodgetts et al, 2008) y la variabilidad de otros genes suele ser suficiente para distinguir entre cepas estrechamente relacionadas (Arnaud et al, 2017;Hodgetts et al, 2008;, Davis et al, 2018.…”