coexistence of symbiosis and pathogenicity-determining genes in Rhizobium rhizogenes strains enables them to induce nodules and tumors or hairy roots in plants

• Published in: Molecular plant-microbe interactions Vol. 18; no. 12; pp. 1325 - 1332
• Main Authors: Velazquez, E, Peix, A, Zurdo-Pineiro, J.L, Palomo, J.L, Mateos, P.F, Rivas, R, Munoz-Adelantado, E, Toro, N, Garcia-Benavides, P, Martinez-Molina, E
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.12.2005; The American Phytopathological Society
• Subjects: Agronomy. Soil science and plant productions; Bacterial plant pathogens; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; Economic plant physiology; endosymbionts; fibrous roots; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; genes; microbial genetics; Molecular Sequence Data; nodulation; nucleotide sequences; pathogenicity; Phaseolus - metabolism; Phaseolus - microbiology; Phaseolus vulgaris; Phylogeny; Phytopathology. Animal pests. Plant and forest protection; plant pathogenic bacteria; Plant Roots - microbiology; plant tumors; Plasmids - genetics; Rhizobiaceae; Rhizobium; Rhizobium - classification; Rhizobium - genetics; Rhizobium - pathogenicity; Rhizobium - physiology; Rhizobium rhizogenes; RNA, Ribosomal, 16S - genetics; root hairs; root nodules; Sinorhizobium; strain differences; strains; symbiosis; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Symbiosis - genetics; Virulence - genetics; Symbiosis; Microbiology; Root; Plant nodule; Rhizobium; Phylogeny; Symbiont; Strain; Plasmid; Pathogenicity; Grain legume; Leguminosae; Vegetable crop; Gene; Phaseolus vulgaris; Dicotyledones; Angiospermae; Nitrogen fixation; Bacteria; Environment; Spermatophyta; Rhizobiaceae
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/mpmi-18-1325

Bacteria belonging to the family Rhizobiaceae may establish beneficial or harmful relationships with plants. The legume endosymbionts contain nod and nif genes responsible for nodule formation and nitrogen fixation, respectively, whereas the pathogenic strains carry vir genes responsible for the formation of tumors or hairy roots. The symbiotic and pathogenic strains currently belong to different species of the genus Rhizobium and, until now, no strains able to establish symbiosis with legumes and also to induce tumors or hairy roots in plants have been reported. Here, we report for the first time the occurrence of two rhizobial strains (163C and ATCC11325T) belonging to Rhizobium rhizogenes able to induce hairy roots or tumors in plants and also to nodulate Phaseolus vulgaris under natural environmental conditions. Symbiotic plasmids (pSym) containing nod and nif genes and pTi- or pRi-type plasmids containing vir genes were found in these strains. The nodD and nifH genes of the strains from this study are phylogenetically related to those of Sinorhizobium strains nodulating P. vulgaris. The virA and virB4 genes from strain 163C are phylogenetically related to those of R. tumefaciens C58, whereas the same genes from strain ATCC 11325T are related to those of hairy root-inducing strains. These findings may be of high relevance for the better understanding of plant-microbe interactions and knowledge of rhizobial phylogenetic history.