Multilocus genotyping identifies a highly homogeneous phytoplasma lineage associated with sweet cherry virescence disease in China and its carriage by an erythroneurine leafhopper

Phytoplasmas are a diverse group of insect-transmitted, cell wall-less bacteria that colonize plant phloem sieve elements and cause numerous diseases in economically important crops. Living a trans-kingdom parasitic life, phytoplasmas possess dynamic genomes and evolve rapidly toward formation of distinct ecological lineages in their adaptation to specific ecological niches. In an effort aimed at identification of the etiological agent responsible for a repeatedly-occurring sweet cherry virescence (SCV) disease in China, we found that the SCV disease was consistently associated with infection by a phytoplasma belonging to subgroup B of the elm yellows phytoplasma group (16SrV-B). Further analysis of genetic loci that encode important phytoplasma cellular components, including an array of ribosomal proteins and preprotein translocase subunit SecY, revealed that the SCV phytoplasma was essentially indistinguishable from the subgroup 16SrV-B phytoplasma strains responsible for jujube witches'-broom (JWB) disease and diseases of many other plants. Evidence gathered in the present study indicated that SCV-JWB phytoplasma strains formed a highly homogenous ecological lineage. The study also revealed that a polyphagous leafhopper, TáoyÄ«diǎnyèchán (桃一点叶蝉 in Chinese and often being cited as Erythroneura sudra), was able to carry the SCV phytoplasma, emphasizing a need to investigate whether this erythroneurine leafhopper plays a role in spreading the SCV phytoplasma among sweet cherry plants.