Multilocus Genotyping Reveals New Molecular Markers for Differentiating Distinct Genetic Lineages among “<i>Candidatus</i> Phytoplasma Solani” Strains Associated with Grapevine Bois Noir
Alessandro Passera,
Yan Zhao,
Sergio Murolo,
Roberto Pierro,
Emilija Arsov,
Nicola Mori,
Abdelhameed Moussa,
Maria R. Silletti,
Paola Casati,
Alessandra Panattoni,
Wei Wei,
Sasa Mitrev,
Alberto Materazzi,
Andrea Luvisi,
Gianfranco Romanazzi,
Piero A. Bianco,
Robert E. Davis,
Fabio Quaglino
Affiliations
Alessandro Passera
Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, 20133 Milano, Italy
Yan Zhao
Molecular Plant Pathology Laboratory, USDA-Agriculture Research Service, Beltsville, MD 20705, USA
Sergio Murolo
Department of Agricultural, Food and Environmental Sciences, Marche Polytechnic University, 60131 Ancona, Italy
Roberto Pierro
Department of Agriculture, Food and Environment, University of Pisa, 56124 Pisa, Italy
Emilija Arsov
Department for Plant and Environment Protection, Faculty of Agriculture, Goce Delcev University, Štip 2000, North Macedonia
Nicola Mori
Department of Biotechnology, University of Verona, 37134 Verona, Italy
Abdelhameed Moussa
Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, 20133 Milano, Italy
Maria R. Silletti
Centro di Ricerca e Sperimentazione in Agricoltura Basile Caramia, 70010 Locorotondo, Italy
Paola Casati
Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, 20133 Milano, Italy
Alessandra Panattoni
Department of Agriculture, Food and Environment, University of Pisa, 56124 Pisa, Italy
Wei Wei
Molecular Plant Pathology Laboratory, USDA-Agriculture Research Service, Beltsville, MD 20705, USA
Sasa Mitrev
Department for Plant and Environment Protection, Faculty of Agriculture, Goce Delcev University, Štip 2000, North Macedonia
Alberto Materazzi
Department of Agriculture, Food and Environment, University of Pisa, 56124 Pisa, Italy
Andrea Luvisi
Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
Gianfranco Romanazzi
Department of Agricultural, Food and Environmental Sciences, Marche Polytechnic University, 60131 Ancona, Italy
Piero A. Bianco
Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, 20133 Milano, Italy
Robert E. Davis
Molecular Plant Pathology Laboratory, USDA-Agriculture Research Service, Beltsville, MD 20705, USA
Fabio Quaglino
Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, 20133 Milano, Italy
Grapevine Bois noir (BN) is associated with infection by “Candidatus Phytoplasma solani” (CaPsol). In this study, an array of CaPsol strains was identified from 142 symptomatic grapevines in vineyards of northern, central, and southern Italy and North Macedonia. Molecular typing of the CaPsol strains was carried out by analysis of genes encoding 16S rRNA and translation elongation factor EF-Tu, as well as eight other previously uncharacterized genomic fragments. Strains of tuf-type a and b were found to be differentially distributed in the examined geographic regions in correlation with the prevalence of nettle and bindweed. Two sequence variants were identified in each of the four genomic segments harboring hlyC, cbiQ-glyA, trxA-truB-rsuA, and rplS-tyrS-csdB, respectively. Fifteen CaPsol lineages were identified based on distinct combinations of sequence variations within these genetic loci. Each CaPsol lineage exhibited a unique collective restriction fragment length polymorphism (RFLP) pattern and differed from each other in geographic distribution, probably in relation to the diverse ecological complexity of vineyards and their surroundings. This RFLP-based typing method could be a useful tool for investigating the ecology of CaPsol and the epidemiology of its associated diseases. Phylogenetic analyses highlighted that the sequence variants of the gene hlyC, which encodes a hemolysin III-like protein, separated into two clusters consistent with the separation of two distinct lineages on the basis of tufB gene sequences. Alignments of deduced full protein sequences of elongation factor-Tu (tufB gene) and hemolysin III-like protein (hlyC gene) revealed the presence of critical amino acid substitutions distinguishing CaPsol strains of tuf-type a and b. Findings from the present study provide new insights into the genetic diversity and ecology of CaPsol populations in vineyards.
