Garnier, Monique

Abstract Phlo.mo.bac.ter. Gr. n. phlomos bark; Gr. n. bakterion a small rod; M.L. neut. Phlomobacter rod in the bark. Filamentous bacteria occurring in the sieve tubes of phloem tissue of plants (Figures 1 and 2). The original description is from infected strawberry plants ( Fragaria × ananassa ) showing leaf marginal chlorosis and stunting in France (Nourrisseau et al., 1993). Like most other phloem‐restricted bacteria, Candidatus Phlomobacter fragariae has resisted in vitro cultivation. The mol % G + C of the DNA is : not determined. Type species : Candidatus Phlomobacter fragariae Zreik, Bové and Garnier 1998, 260. Taxonomic and Nomenclature Notes According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus Candidatus Phlomobacter is: misspelling (and no standing) (last update, February 2025) * . LPSN classification: Bacteria / Pseudomonadati / Pseudomonadota / Gammaproteobacteria / Enterobacterales / Enterobacteriaceae / Candidatus Phlomobacter Candidatus Phlomobacter 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

ABSTRACT Marginal chlorosis is a new disease of strawberry in which the uncultured phloem-restricted proteobacterium “ Candidatus Phlomobacter fragariae” is involved. In order to identify the insect(s) vector(s) of this bacterium, homopteran insects have been captured. Because a PCR test based on the 16S rRNA gene (rDNA) applied to these insects was unable to discriminate between “P. fragariae” and other insect-associated proteobacteria, isolation of “P. fragariae” genes other than 16S rDNA was undertaken. Using comparative randomly amplified polymorphic DNAs, an amplicon was specifically amplified from “P. fragariae”-infected strawberry plants. It encodes part of a “P. fragariae” open reading frame sharing appreciable homology with the spoT gene from other proteobacteria. A spoT -based PCR test combined with restriction fragment length polymorphisms was developed and was able to distinguish “P. fragariae” from other insect bacteria. None of the many leafhoppers and psyllids captured during several years in and around infected strawberry fields was found to carry “P. fragariae.” Interestingly however, the “P. fragariae” spoT sequence could be easily detected in whiteflies proliferating on “P. fragariae”-infected strawberry plants under confined greenhouse conditions but not on control whiteflies, indicating that these insects can become infected with the bacterium.