Department of Agricultural and Food Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy.
Sporometrics Inc., Toronto, Ontario, Canada.
Int J Syst Evol Microbiol. 2022 Apr;72(4). doi: 10.1099/ijsem.0.005353.
The genus ' Phytoplasma' was proposed to accommodate cell wall-less bacteria that are molecularly and biochemically incompletely characterized, and colonize plant phloem and insect vector tissues. This provisional classification is highly relevant due to its application in epidemiological and ecological studies, mainly aimed at keeping the severe phytoplasma plant diseases under control worldwide. Given the increasing discovery of molecular diversity within the genus '. Phytoplasma', the proposed guidelines were revised and clarified to accommodate those '. Phytoplasma' species strains sharing >98.65 % sequence identity of their full or nearly full 16S rRNA gene sequences, obtained with at least twofold coverage of the sequence, compared with those of the reference strain of such species. Strains sharing <98.65 % sequence identity with the reference strain but >98.65 % with other strain(s) within the same '. Phytoplasma' species should be considered related strains to that '. Phytoplasma' species. The guidelines herein, keep the original published reference strains. However, to improve '. Phytoplasma' species assignment, complementary strains are suggested as an alternative to the reference strains. This will be implemented when only a partial 16S rRNA gene and/or a few other genes have been sequenced, or the strain is no longer available for further molecular characterization. Lists of '. Phytoplasma' species and alternative reference strains described are reported. For new '. Phytoplasma' species that will be assigned with identity ≥98.65 % of their 16S rRNA gene sequences, a threshold of 95 % genome-wide average nucleotide identity is suggested. When the whole genome sequences are unavailable, two among conserved housekeeping genes could be used. There are 49 officially published ' Phytoplasma' species, including '. P. cocostanzaniae' and '. P. palmae' described in this manuscript.
“植原体”属被提议用于容纳细胞壁缺失的细菌，这些细菌在分子和生化方面尚未完全确定，定植在植物韧皮部和昆虫载体组织中。这种临时性分类非常重要，因为它应用于流行病学和生态学研究，主要旨在控制全世界严重的植原体植物病害。鉴于该属内分子多样性的不断发现，修订并澄清了提出的准则，以适应那些具有与其参考菌株的全长或近乎全长 16S rRNA 基因序列的序列同一性> 98.65％的“植原体”物种菌株，这些序列是通过至少两倍的序列覆盖率获得的，与该物种参考菌株相比。与参考菌株的序列同一性< 98.65％但与同一“植原体”物种内的其他菌株的序列同一性> 98.65％的菌株应被视为与该“植原体”物种相关的菌株。本准则保留了原始发表的参考菌株。但是，为了提高“植原体”物种的分类，可以建议使用补充菌株作为参考菌株的替代物。这将在仅对部分 16S rRNA 基因和/或少数其他基因进行测序，或者该菌株不再可用于进一步分子特征分析时实施。报告了“植原体”物种和替代参考菌株的列表。对于将被分配给与其 16S rRNA 基因序列的同一性≥98.65％的新“植原体”物种，建议使用全基因组平均核苷酸同一性的阈值为 95％。当全基因组序列不可用时，可以使用两个保守的管家基因之一。本文描述了 49 种正式公布的“植原体”物种，包括“P. cocostanzaniae”和“P. palmae”。
