1. |
Chen WM,
de Faria SM,
Straliotto R,
Pitard RM,
Simões-Araùjo JL,
Chou JH,
Chou YJ,
Barrios E,
Prescott AR,
Elliott GN,
Sprent JI,
Young JP,
James EK,
( 2005 ) Proof that Burkholderia strains form effective symbioses with legumes: a study of novel Mimosa-nodulating strains from South America. PMID : 16269788 : DOI : 10.1128/AEM.71.11.7461-7471.2005 PMC : PMC1287612 Abstract >>
Twenty Mimosa-nodulating bacterial strains from Brazil and Venezuela, together with eight reference Mimosa-nodulating rhizobial strains and two other beta-rhizobial strains, were examined by amplified rRNA gene restriction analysis. They fell into 16 patterns and formed a single cluster together with the known beta-rhizobia, Burkholderia caribensis, Burkholderia phymatum, and Burkholderia tuberum. The 16S rRNA gene sequences of 15 of the 20 strains were determined, and all were shown to belong to the genus Burkholderia; four distinct clusters could be discerned, with strains isolated from the same host species usually clustering very closely. Five of the strains (MAP3-5, Br3407, Br3454, Br3461, and Br3469) were selected for further studies of the symbiosis-related genes nodA, the NodD-dependent regulatory consensus sequences (nod box), and nifH. The nodA and nifH sequences were very close to each other and to those of B. phymatum STM815, B. caribensis TJ182, and Cupriavidus taiwanensis LMG19424 but were relatively distant from those of B. tuberum STM678. In addition to nodulating their original hosts, all five strains could also nodulate other Mimosa spp., and all produced nodules on Mimosa pudica that had nitrogenase (acetylene reduction) activities and structures typical of effective N2-fixing symbioses. Finally, both wild-type and green fluorescent protein-expressing transconjugant strains of Br3461 and MAP3-5 produced N2-fixing nodules on their original hosts, Mimosa bimucronata (Br3461) and Mimosa pigra (MAP3-5), and hence this confirms strongly that Burkholderia strains can form effective symbioses with legumes.
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2. |
Dall'Agnol RF,
Bournaud C,
de Faria SM,
Béna G,
Moulin L,
Hungria M,
( 2017 ) Genetic diversity of symbiotic Paraburkholderia species isolated from nodules of Mimosa pudica (L.) and Phaseolus vulgaris (L.) grown in soils of the Brazilian Atlantic Forest (Mata Atl?ntica). PMID : 28334155 : DOI : 10.1093/femsec/fix027 Abstract >>
Some species of the genus Paraburkholderia that are able to nodulate and fix nitrogen in symbiosis with legumes are called �]-rhizobia and represent a group of ecological and biotechnological importance. We used Mimosa pudica and Phaseolus vulgaris to trap 427 rhizobial isolates from rhizospheric soil of Mimoseae trees in the Brazilian Atlantic Forest. Eighty-four representative strains were selected according to the 16S rRNA haplotypes and taxonomically characterized using a concatenated 16S rRNA-recA phylogeny. Most strains were assembled in the genus Paraburkholderia, including Paraburkholderia sabiae and Pa. nodosa. Mesorhizobium (�\-rhizobia) and Cupriavidus (�]-rhizobia) were also isolated, but in smaller proportions. Multilocus sequence analysis and BOX-PCR analyses indicated that six clusters of Paraburkholderia represent potential new species. In the phylogenetic analysis of the nodC gene, the majority of the strains were positioned in the same groups as in the 16S rRNA-recA tree, indicative of stability and vertical inheritance, but we also identified horizontal transfer of nodC in Pa. sabiae. All �\- and �]-rhizobial species were trapped by both legumes, although preferences of the host plants for specific rhizobial species have been observed.
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3. |
Bournaud C,
de Faria SM,
dos Santos JM,
Tisseyre P,
Silva M,
Chaintreuil C,
Gross E,
James EK,
Prin Y,
Moulin L,
( 2013 ) Burkholderia species are the most common and preferred nodulating symbionts of the Piptadenia group (tribe Mimoseae). PMID : 23691052 : DOI : 10.1371/journal.pone.0063478 PMC : PMC3655174 Abstract >>
Burkholderia legume symbionts (also called �\-rhizobia) are ancient in origin and are the main nitrogen-fixing symbionts of species belonging to the large genus Mimosa in Brazil. We investigated the extent of the affinity between Burkholderia and species in the tribe Mimoseae by studying symbionts of the genera Piptadenia (P.), Parapiptadenia (Pp.), Pseudopiptadenia (Ps.), Pityrocarpa (Py.), Anadenanthera (A.) and Microlobius (Mi.), all of which are native to Brazil and are phylogenetically close to Mimosa, and which together with Mimosa comprise the "Piptadenia group". We characterized 196 strains sampled from 18 species from 17 locations in Brazil using two neutral markers and two symbiotic genes in order to assess their species affiliations and the evolution of their symbiosis genes. We found that Burkholderia are common and highly diversified symbionts of species in the Piptadenia group, comprising nine Burkholderia species, of which three are new ones and one was never reported as symbiotic (B. phenoliruptrix). However, �\-rhizobia were also detected and were occasionally dominant on a few species. A strong sampling site effect on the rhizobial nature of symbionts was detected, with the symbiont pattern of the same legume species changing drastically from location to location, even switching from �] to �\-rhizobia. Coinoculation assays showed a strong affinity of all the Piptadenia group species towards Burkholderia genotypes, with the exception of Mi. foetidus. Phylogenetic analyses of neutral and symbiotic markers showed that symbiosis genes in Burkholderia from the Piptadenia group have evolved mainly through vertical transfer, but also by horizontal transfer in two species.
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