Phytoplasma disease “Bois noir” in Crimea: diagnosis of the pathogen

In 2018-2019, grape leaf samples with symptoms of yellowing (reddening) and leaf rolling collected from grapevines of different regions of Crimea were tested for the presence of phytoplasma using the “nested”PCR with primer pairs P1/16S-Sr and R16F2n/R16R2. Phytoplasmas were detected in 91% grape samples of 2018 and 46% samples of 2019. Genotyping performed by restriction fragment length polymorphism analysis for three genes: ribosomal (16S rRNA), the tuf gene encoding the elongation factor EF-Tu, and the vmp1 gene encoding a membrane protein, showed that the phytoplasmas isolated from all samples were related to the species Candidatus Phytoplasma solani, type “b”. Polymorphism was observed only for the vmp1 gene. The electrophoretic profiles of grape phytoplasma of 2018 (‘Chardonnay’ variety) differed from those of grape phytoplasma of 2019 (‘Pinot Noir’ and ‘Verdelho’ varieties), as well as from the profiles published in well-known works, which indicates the genetic diversity