Abstract
Phy.to.plas‐ma. Gr. masc. n.
phytos
a plant; N.L. neut. n.
Phytoplasma
a form from a plant.
Phytoplasmas are wall‐less, nutritionally fastidious, and phytopathogenic prokaryotes 0.2–0.8 μm in diameter that morphologically resemble nonhelical members of the class
Mollicutes
. Sequencing of nearly full‐length PCR‐amplified 16S rRNA genes, combined with earlier studies, provided the first comprehensive phylogeny of the organisms and showed that they constitute a unique, monophyletic clade within the
Mollicutes
. These organisms are most closely related to members of the genus
Acholeplasma
within the
Anaeroplasma
clade as defined by Weisburg et al. Despite decades of efforts and recent progress, sustained pure culture in cell‐free media has not yet been demonstrated for any phytoplasma. Their genome sizes have been estimated to range from 530 to 1,350 kb, and the DNA G + C content is about 23–30 mol%. The presence of a characteristic oligonucleotide sequence in the 16S rRNA gene, CAA GAY BAT KAT GTK TAG CYG GDC T, and standard codon usage indicate that phytoplasmas represent a distinct genus‐level taxon for which the name ‘
Candidatus
Phytoplasma’ has been adopted. At present, for any subtaxa within the provisional genus, the designation ‘
Candidatus
’ must still be used.
DNA G + C content (mol%)
: 23–29.
Taxonomic and Nomenclature Notes
According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus
Candidatus Phytoplasma
is: preferred name (not correct name) (last update, February 2025)
*
.
LPSN classification:
Bacteria
/
Bacillati
/
Mycoplasmatota
/
Mollicutes
/
Acholeplasmatales
/
Acholeplasmataceae
/
Candidatus Phytoplasma
Candidatus Phytoplasma
could not be recovered in GTDB
**
.
*
Meier‐Kolthoff
et al. (
2022
).
Nucleic Acids Res
,
50
,
D801
–
D807
; DOI:
10.1093/nar/gkab902
**
Parks
et al. (
2022
).
Nucleic Acids Res
,
50
,
D785
–
D794
; DOI:
10.1093/nar/gkab776