Skip to main content
ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Molecular Plant Pathology Laboratory » Research » Publications at this Location » Publication #416286
Research Project: Omics-Based Approach to Detection, Identification, and Systematics of Plant Pathogenic Phytoplasmas and Spiroplasmas

Location: Molecular Plant Pathology Laboratory

Title: Advances and challenges in phytoplasma taxonomy

Author
item Zhao, Yan
item Wei, Wei

Submitted to: CABI Agriculture and Bioscience (CABI A&B)
Publication Type: Book / Chapter
Publication Acceptance Date: 1/20/2025
Publication Date: 10/13/2025
Citation: Zhao, Y., Wei, W. 2025. Advances and challenges in phytoplasma taxonomy. In: Wei, W. editor. Phytoplasmas: Genomes, Plant Hosts and Vectors. 2nd edition.CABI Agriculture and Bioscience (CABI A&B). 4:36-68. https://doi.org/10.1079/9781800627031.0004.
DOI: https://doi.org/10.1079/9781800627031.0004

Interpretive Summary:

Technical Abstract: Phytoplasmas are non-helical, mycoplasma-like cell wall-less bacteria that have immense economic and environmental impacts as they are known to be responsible for numerous diseases in nearly one thousand plant species worldwide. Phytoplasmas are diverse genetically and ecologically. An informative taxonomic system is essential to understand the breadth of phytoplasma diversity and the uniqueness of each species. However, due to their limited metabolic capacity and high host dependency, phytoplasmas cannot be cultured in vitro and therefore are excluded from polyphasic characterization. Molecular analyses of conserved gene sequences and. more recently, the whole-genome sequence-based approaches have become primary means for phytoplasma characterization. This chapter provides an overview of the history and the current status of phytoplasma taxonomy, including their nomenclature, classification, and identification. The topics of the chapter include: the 2004 original and 2022 revised guidelines for ‘Candidatus Phytoplasma species’ delineation; opinions on the taxonomic rank of phytoplasmas; the continued need of the pragmatic group/subgroup classification scheme; the criteria for recognizing new phytoplasma groups and subgroups; and the most common practices as well as sophisticated new molecular approaches for phytoplasma identification. While recent advances have addressed some of the important issues, challenges still exist to improve the current phytoplasma taxonomy in the post-genomic era.