Recovery of nonpathogenic mutant bacteria from tumors caused by several Agrobacterium tumefaciens strains: a frequent event?
Fecha
2009Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Impacto
|
10.1128/aem.01867-08
Resumen
We have evaluated the interaction that bacterial genotypes and plant hosts have with the loss of pathogenicity in
tumors, using seven Agrobacterium tumefaciens strains inoculated on 12 herbaceous and woody hosts. We performed
a screening of the agrobacteria present inside the tumors, looking for nonpathogenic strains, and found a high
variability of those strains in this niche. To verify the orig ...
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We have evaluated the interaction that bacterial genotypes and plant hosts have with the loss of pathogenicity in
tumors, using seven Agrobacterium tumefaciens strains inoculated on 12 herbaceous and woody hosts. We performed
a screening of the agrobacteria present inside the tumors, looking for nonpathogenic strains, and found a high
variability of those strains in this niche. To verify the origin of the putative nonpathogenic mutant bacteria, we
applied an efficient, reproducible, and specific randomly amplified polymorphic DNA analysis method. In contrast
with previous studies, we recovered a very small percentage (0.01%) of nonpathogenic strains that can be considered
true mutants. Of 5,419 agrobacterial isolates examined, 662 were nonpathogenic in tomato, although only 7 (from
pepper and tomato tumors induced by two A. tumefaciens strains) could be considered to derive from the inoculated
strain. Six mutants were affected in the transferred DNA (T-DNA) region; one of them contained IS426 inserted into
the iaaM gene, whereas the whole T-DNA region was apparently deleted in three other mutants, and the virulence
of the remaining two mutants was fully restored with the T-DNA genes as well. The plasmid profile was altered in
six of the mutants, with changes in the size of the Ti plasmid or other plasmids and/or the acquisition of new
plasmids. Our results also suggest that the frequent occurrence of nonpathogenic clones in the tumors is probably
due to the preferential growth of nonpathogenic agrobacteria, of either endophytic or environmental origin, but
different from the bacterial strain inducing the tumor. [--]
Materias
Agrobacterium tumefaciens,
Nonpathogenic mutant bacteria,
Tumors
Editor
American Society for Microbiology
Publicado en
Applied and Environmental Microbiology, Oct. 2009, Vol. 75, No. 20, p. 6504–6514
Departamento
Universidad Pública de Navarra. Departamento de Producción Agraria /
Nafarroako Unibertsitate Publikoa. Nekazaritza Ekoizpena Saila
Versión del editor
Entidades Financiadoras
This research was supported partially by project INIA (grant SC93-
117) of the Spanish Ministry of Agriculture and by COST Action 873
(European Union). Pablo Llop has a contract from the Ministry of
Education and INIA, with funding from the European Union (Social
European Funding).