Genetic Diversity of Flavescence Dorée Phytoplasmas at the Vineyard Scale

• Published in: Applied and environmental microbiology Vol. 85; no. 10; pp. e03123 - 18
• Main Authors: Rossi, Marika, Pegoraro, Mattia, Ripamonti, Matteo, Abbà, Simona, Beal, Dylan, Giraudo, Alessia, Veratti, Flavio, Malembic-Maher, Sylvie, Salar, Pascal, Bosco, Domenico, Marzachì, Cristina
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 15-05-2019
• Subjects: Agricultural ecosystems; Animals; Clematis; Clematis - microbiology; DnaK protein; Epidemiology; Farms; Genetic diversity; Genetic markers; Genetic Variation; Genotypes; Grapevines; Hemiptera - microbiology; Insects; Italy; Life Sciences; Loci; Markers; Phytopathology and phytopharmacy; Phytoplasma; Phytoplasma - genetics; Phytoplasma - physiology; Plant Diseases - microbiology; Plant Microbiology; Population genetics; Population studies; Populations; Rootstocks; Strains (organisms); Variability; Vegetal Biology; Vineyards; Vitis - microbiology; Vitis vinifera; Wine; Wineries & vineyards; Wines; Italy; Scaphoideus titanus; Clematis; dnaK; malG; Vitis vinifera; vmpA
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.03123-18

To study the role of wild areas around the vineyards in the epidemiology of flavescence dorée (FD) and track the origin of new foci, two phytoplasma genetic markers,
and
, were developed for FD phytoplasma (FDp) characterization. The two genes and the
locus were used to genetically characterize FDp populations at seven agroecosystems of a wine-growing Italian region.
, "gone-wild"
and rootstocks,
spp., and
adults were sampled within and outside the vineyards. A range of genotypes infecting the different hosts of the FDp epidemiological cycle was found. Type FD-C isolates were fairly homogeneous compared to type FD-D ones. Most of the FD-D variability was correlated with the
sequence, and a duplication of this locus was demonstrated for this strain. Coinfection with FD-C and FD-D strains was rare, suggesting possible competition between the two. Similar levels of FDp genetic variation recorded for grapevines or leafhoppers of cultivated and wild areas and co-occurrence of many FDp genotypes inside and outside the vineyards supported the idea of the importance of wild or abandoned
plants and associated
insects in the epidemiology of the disease. Genetic profiles of FDp found in
were never found in the other hosts, indicating that this species does not take part in the disease cycle in the area. Due to the robustness of analyses using
for discriminating between FD-C and FD-D strains and the high variability of
sequences, these are efficient markers to study FDp populations and epidemiology at a small geographical scale.
Flavescence dorée, a threatening disease of grapevine caused by FD phytoplasma (FDp), is distributed within the most important wine-producing areas of Europe and has severe effects on both vineyard productivity and landscape management. FDp is a quarantine pest in Europe, and despite the efforts to contain the pathogen, the disease is still spreading. In this work, new genetic markers for the fine genetic characterization of FDp at local scale are presented. Our findings improve the knowledge of FDp epidemiological cycle and offer the possibility of tracking the route of the FDp infection. In particular, due to its high genetic variability, one of the newly developed markers could be sufficient to track the origin of new infection foci, either from the wild areas or from nurseries.