Articles
MARGINAL CHLOROSIS OF STRAWBERRY: TRANSMISSION OF “CANDIDATUS PHLOMOBACTER FRAGARIAE” TO PERIWINKLE BY THE PLANTHOPPER CIXIUS WAGNERI (CHINA) AND CHARACTERIZATION OF THE ISOLATE
Article number
656_12
Pages
87 – 92
Language
English
Abstract
The uncultured phloem-restricted γ 3-proteobacterium “Candidatus Phlomobacter fragariae” is associated with marginal chlorosis of strawberry in French production fields.
Strawberry isolates could not be maintained under greenhouse conditions, since the infected plants died and graft transmission could not be achieved.
The recent identification of the planthopper Cixius wagneri as vector of this proteobacterium, allowed the transmission of “Ca P. fragariae” to Catharanthus roseus periwinkle, providing the first “Ca P. fragariae” reference isolate.
Electron microscopy, 16S-rDNA and spoT PCR amplification confirmed the presence of “Ca P. fragariae” in diseased periwinkles.
Graft transmission of infected shoots to healthy periwinkle seedlings led to stable maintenance of isolate LG2001 and reproducible observation of symptoms expression.
Recent description of 16S-rDNA sequences from other proteobacteria revealed that “Ca P. fragariae” was related closely to a proteobacterium associated with a sugarbeet disease and transmitted by another planthopper as well as to secondary symbionts of whiteflies and psyllids.
A remarkable feature in “Ca P. fragariae” 16S-rDNA sequence was a unique 36 bp deletion at the beginning of the gene . In order to better characterize our reference isolate, we further studied its 16S-rDNA. Because at least 11 “Ca P. fragariae” different 16S-rDNA copies could be found, we concluded that isolate LG 2001 is either a mixed infection of two different “Ca P. fragariae” strains or possesses more than eleven 16S-rDNA copies, and only some have the 36-bp deletion at the beginning of the gene.
Strawberry isolates could not be maintained under greenhouse conditions, since the infected plants died and graft transmission could not be achieved.
The recent identification of the planthopper Cixius wagneri as vector of this proteobacterium, allowed the transmission of “Ca P. fragariae” to Catharanthus roseus periwinkle, providing the first “Ca P. fragariae” reference isolate.
Electron microscopy, 16S-rDNA and spoT PCR amplification confirmed the presence of “Ca P. fragariae” in diseased periwinkles.
Graft transmission of infected shoots to healthy periwinkle seedlings led to stable maintenance of isolate LG2001 and reproducible observation of symptoms expression.
Recent description of 16S-rDNA sequences from other proteobacteria revealed that “Ca P. fragariae” was related closely to a proteobacterium associated with a sugarbeet disease and transmitted by another planthopper as well as to secondary symbionts of whiteflies and psyllids.
A remarkable feature in “Ca P. fragariae” 16S-rDNA sequence was a unique 36 bp deletion at the beginning of the gene . In order to better characterize our reference isolate, we further studied its 16S-rDNA. Because at least 11 “Ca P. fragariae” different 16S-rDNA copies could be found, we concluded that isolate LG 2001 is either a mixed infection of two different “Ca P. fragariae” strains or possesses more than eleven 16S-rDNA copies, and only some have the 36-bp deletion at the beginning of the gene.
Authors
J.L. Danet, P. Salar, B. Batailler, X. Foissac, M. Garnier
Keywords
proteobacteria, insect vector, 16S-rDNA, Fragaria x ananassa, Fulguromorpha, Cixiidae
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