title: Nodulation of Sesbania species by Rhizobium (Agrobacterium) strain IRBG74 and other rhizobia.
abstract: Concatenated sequence analysis with 16S rRNA, rpoB and fusA genes identified a bacterial strain (IRBG74) isolated from root nodules of the aquatic legume Sesbania cannabina as a close relative of the plant pathogen Rhizobium radiobacter (syn. Agrobacterium tumefaciens). However, DNA:DNA hybridization with R. radiobacter, R. rubi, R. vitis and R. huautlense gave only 44%, 5%, 8% and 8% similarity respectively, suggesting that IRBG74 is potentially a new species. Additionally, it contained no vir genes and lacked tumour-forming ability, but harboured a sym-plasmid containing nifH and nodA genes similar to those in other Sesbania symbionts. Indeed, IRBG74 effectively nodulated S. cannabina and seven other Sesbania spp. that nodulate with Ensifer (Sinorhizobium)/Rhizobium strains with similar nodA genes to IRBG74, but not species that nodulate with Azorhizobium or Mesorhizobium. Light and electron microscopy revealed that IRBG74 infected Sesbania spp. via lateral root junctions under flooded conditions, but via root hairs under non-flooded conditions. Thus, IRBG74 is the first confirmed legume-nodulating symbiont from the Rhizobium (Agrobacterium) clade. Cross-inoculation studies with various Sesbania symbionts showed that S. cannabina could form fully effective symbioses with strains in the genera Rhizobium and Ensifer, only ineffective ones with Azorhizobium strains, and either partially effective (Mesorhizobium huakii) or ineffective (Mesorhizobium plurifarium) symbioses with Mesorhizobium. These data are discussed in terms of the molecular phylogeny of Sesbania and its symbionts.
authors: School of Applied Sciences, Ellison Building, University of Northumbria, Newcastle-upon-Tyne, UK.
authors: Stephen P
authors: SP
authors: Cummings
authors: Prasad
authors: P
authors: Gyaneshwar
authors: Pablo
authors: P
authors: Vinuesa
authors: Frank T
authors: FT
authors: Farruggia
authors: Mitchell
authors: M
authors: Andrews
authors: David
authors: D
authors: Humphry
authors: Geoffrey N
authors: GN
authors: Elliott
authors: Andrew
authors: A
authors: Nelson
authors: Caroline
authors: C
authors: Orr
authors: Deborah
authors: D
authors: Pettitt
authors: Gopit R
authors: GR
authors: Shah
authors: Scott R
authors: SR
authors: Santos
authors: Hari B
authors: HB
authors: Krishnan
authors: David
authors: D
authors: Odee
authors: Fatima M S
authors: FM
authors: Moreira
authors: Janet I
authors: JI
authors: Sprent
authors: J Peter W
authors: JP
authors: Young
authors: Euan K
authors: EK
authors: James
mesh_terms: D000217:Acyltransferases / Q000032:analysis / Q000235:genetics; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D009586:Nitrogen Fixation; D010088:Oxidoreductases / Q000032:analysis / Q000235:genetics; D020653:Peptide Elongation Factor G / Q000032:analysis / Q000235:genetics; D010802:Phylogeny; D010957:Plasmids / Q000032:analysis / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D012231:Rhizobium / Q000235:genetics* / Q000648:ultrastructure; D053204:Root Nodules, Plant / Q000382:microbiology* / Q000648:ultrastructure; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D049931:Sesbania / Q000382:microbiology* / Q000648:ultrastructure; D013045:Species Specificity; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D020653:Peptide Elongation Factor G; D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; C029130:nitrogenase reductase; D000217:Acyltransferases; C060770:NodA protein, Rhizobiales