Identification of new -J and -K 16SrXII subgroups and distinct single nucleotide polymorphism genetic lineages among ‘Candidatus Phytoplasma solani’ strains associated with bois noir in Central Italy

Bois noir of grapevines is attributed to infection by ‘ Candidatus Phytoplasma solani’ strains, taxonomic subgroups 16SrXII-A, -F, and -G. Plant-to-plant transmission by polyphagous leafhoppers determined that ‘ Ca . Phytoplasma solani’ strains exist in diverse plant hosts in varied ecosystems, where selection conceivably influences intra-species strain diversity. In this study, virtual restriction fragment length polymorphism (RFLP) and single nucleotide polymorphism (SNP) analyses of 16S rDNA nucleotide sequences, amplified from grapevines and bindweeds in central-eastern Italy, revealed the presence of two new subgroups (16SrXII-J and 16SrXII-K) in the 16SrXII group, and of genetically distinct SNP lineages. Findings from the present and related works report the extensive intra-species diversity among ‘ Ca . Phytoplasma solani’ strains in vineyards, underscoring the need for further studies to investigate relationships between diverse phytoplasma strains and dynamics of bois noir epidemiology.