Multilocus sequence typing of phytoplasmas associated with Flavescence dorée disease in Tuscany vineyards identifies a highly homogeneous lineage in the subgroup 16SrV-C

Authors: PIERRO, ROBERTO - University Of Salerno; Bottner, Kristi; PANATTONI, ALESSANDRA - University Of Pisa; Wei, Wei; MARCONE, CARMINE - University Of Salerno; RIZZO, DOMENICO - Regional Phytosanitary Service; MATERAZZI, ALBERTO - University Of Pisa; QUAGLINO, FABIO - University Of Milan; Zhao, Yan

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2022
Publication Date: 10/5/2022
Citation: Pierro, R., Bottner-Parker, K.D., Panattoni, A., Wei, W., Marcone, C., Rizzo, D., Materazzi, A., Quaglino, F., Zhao, Y. 2022. Multilocus sequence typing of phytoplasmas associated with Flavescence dorée disease in Tuscany vineyards identifies a highly homogeneous lineage in the subgroup 16SrV-C. Crop Protection. 163. Article 106114. https://doi.org/10.1016/j.cropro.2022.106114.
DOI: https://doi.org/10.1016/j.cropro.2022.106114

Interpretive Summary: Flavescence Dorée (FD) is the most threatening grapevine yellows disease in Europe. Despite strict control measures, alarming signs of the spread of the disease in viticultural areas continue to be detected. FD is attributed to infection by a cell wall-less bacterium termed FD phytoplasma. In collaboration with scientists in Italy, ARS researchers at the Beltsville Agricultural Research Center conducted multi-gene comparative analysis on FD phytoplasma strains found in vineyards in Central Italy. The study found that the FD phytoplasma strains in the region constitute a highly homogeneous lineage whose collective genotype is different from previously characterized FD phytoplasmas in Europe. Molecular markers were identified for distinguishing this lineage from other FD phytoplasma lineages. Such molecular markers provide clues to understanding the genetic relationships among different FD phytoplasma lineages present in Europe and are useful for searching potential vectors and reservoirs involved in the spread of the pathogen. The findings will be of interest to research scientists and plant disease diagnosticians who are interested in phytoplasma identification, genetic diversity, and disease management. This information is also useful to regulatory agencies for implementing control measures to prevent exotic phytoplasmas from coming into the U.S.

Technical Abstract: Flavescence dorée (FD) is the most threatening grapevine yellows (GY) disease in Europe. Despite strict control measures, alarming signs of the spread of the disease in viticultural areas continue to be detected. FD is attributed to infection by phytoplasma strains of an incidentally cited species, 'Candidatus Phytoplasma vitis'. In 2017, a GY field survey was carried out in traditional viticulture areas of Tuscany, central Italy. FD phytoplasma (FDp) was detected in 85 GY symptomatic vines, accounting for 17% of a total of 500 symptomatic samples screened. The FDp-positive vines were scattered in 50 vineyards across seven Tuscan provinces, indicating the distribution of FDp has further extended to central and southwestern parts of Tuscany including Florence and Livorno. Multilocus sequence typing of 15 representative FDp strains from six affected vineyards revealed that the Tuscan FDp strains constitute a highly homogeneous lineage within in the subgroup 16SrV-C (FD-C). Single nucleotide polymorphisms (SNPs) were identified in the 16S rRNA, rp, and secY genes of the Tuscan FDp lineage. Such SNP markers provide clues to understanding the genetic relationships among different FDp lineages present in Europe and are useful for searching potential vectors and reservoirs involved in the spread of the FDp in the Tuscan region.