Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia, Università degli Studi, via Celoria 2, 20133 Milan, Italy.
Molecular Plant Pathology Laboratory, USDA-Agricultural Research Service, Beltsville, MD 20705, USA.
Int J Syst Evol Microbiol. 2013 Aug;63(Pt 8):2879-2894. doi: 10.1099/ijs.0.044750-0. Epub 2013 Jan 18.
Phytoplasmas classified in group 16SrXII infect a wide range of plants and are transmitted by polyphagous planthoppers of the family Cixiidae. Based on 16S rRNA gene sequence identity and biological properties, group 16SrXII encompasses several species, including 'Candidatus Phytoplasma australiense', 'Candidatus Phytoplasma japonicum' and 'Candidatus Phytoplasma fragariae'. Other group 16SrXII phytoplasma strains are associated with stolbur disease in wild and cultivated herbaceous and woody plants and with bois noir disease in grapevines (Vitis vinifera L.). Such latter strains have been informally proposed to represent a separate species, 'Candidatus Phytoplasma solani', but a formal description of this taxon has not previously been published. In the present work, stolbur disease strain STOL11 (STOL) was distinguished from reference strains of previously described species of the 'Candidatus Phytoplasma' genus based on 16S rRNA gene sequence similarity and a unique signature sequence in the 16S rRNA gene. Other stolbur- and bois noir-associated ('Ca. Phytoplasma solani') strains shared >99 % 16S rRNA gene sequence similarity with strain STOL11 and contained the signature sequence. 'Ca. Phytoplasma solani' is the only phytoplasma known to be transmitted by Hyalesthes obsoletus. Insect vectorship and molecular characteristics are consistent with the concept that diverse 'Ca. Phytoplasma solani' strains share common properties and represent an ecologically distinct gene pool. Phylogenetic analyses of 16S rRNA, tuf, secY and rplV-rpsC gene sequences supported this view and yielded congruent trees in which 'Ca. Phytoplasma solani' strains formed, within the group 16SrXII clade, a monophyletic subclade that was most closely related to, but distinct from, that of 'Ca. Phytoplasma australiense'-related strains. Based on distinct molecular and biological properties, stolbur- and bois noir-associated strains are proposed to represent a novel species level taxon, 'Ca. Phytoplasma solani'; STOL11 is designated the reference strain.
16SrXII 组中的植原体可感染广泛的植物，并通过粉虱科的多食性粉虱传播。根据 16S rRNA 基因序列同一性和生物学特性，16SrXII 组包括几个种，包括“Candidatus Phytoplasma australiense”、“Candidatus Phytoplasma japonicum”和“Candidatus Phytoplasma fragariae”。其他 16SrXII 组植原体菌株与野生和栽培草本及木本植物的黄脉病和葡萄藤的黑痘病有关（Vitis vinifera L.）。后者菌株被非正式地提议代表一个单独的种，“Candidatus Phytoplasma solani”，但尚未正式描述该分类群。在本工作中，黄脉病 STOL11 （STOL）菌株根据 16S rRNA 基因序列相似性和 16S rRNA 基因中的独特特征序列与先前描述的“Candidatus Phytoplasma”属种的参考菌株区分开来。其他黄脉病和黑痘病相关（“Ca. Phytoplasma solani”）菌株与 STOL11 菌株的 16S rRNA 基因序列相似性>99%，并含有特征序列。“Ca. Phytoplasma solani”是唯一已知由 Hygletes obsoletus 传播的植原体。昆虫媒介和分子特征与不同“Ca. Phytoplasma solani”菌株具有共同特性并代表一个生态上不同的基因库的概念一致。16S rRNA、tuf、secY 和 rplV-rpsC 基因序列的系统发育分析支持这一观点，并产生了一致的树，其中“Ca. Phytoplasma solani”菌株在 16SrXII 分支内形成一个单系亚分支，该亚分支与“Ca. Phytoplasma australiense”相关菌株最密切相关，但与后者不同。基于独特的分子和生物学特性，黄脉病和黑痘病相关菌株被提议代表一个新的种水平分类群，“Ca. Phytoplasma solani”；STOL11 被指定为参考菌株。
