Revealing potential functions of hypothetical proteins induced by genistein in the symbiosis island of Bradyrhizobium japonicum commercial strain SEMIA 5079 (= CPAC 15).

Background: Bradyrhizobium japonicum strain SEMIA 5079 (= CPAC 15) is a nitrogen-fixing symbiont of soybean broadly used in commercial inoculants in Brazil. Its genome has about 50% of hypothetical (HP) protein-coding genes, many in the symbiosis island, raising questions about their putative role on the biological nitrogen fixation (BNF) process. This study aimed to infer functional roles to 15 HP genes localized in the symbiosis island of SEMIA 5079, and to analyze their expression in the presence of a nod-gene inducer.

Phenotypic switching in Candida tropicalis alters host-pathogen interactions in a Galleria mellonella infection model.

Candida tropicalis is a human pathogen associated with high mortality rates. We have reported a switching system in C. tropicalis consisting of five morphotypes - the parental, switch variant (crepe and rough), and revertant (crepe and rough) strains, which exhibited altered virulence in a Galleria mellonella model.

Comparative genomics of Bradyrhizobium japonicum CPAC 15 and Bradyrhizobium diazoefficiens CPAC 7: elite model strains for understanding symbiotic performance with soybean.

Background: The soybean-Bradyrhizobium symbiosis can be highly efficient in fixing nitrogen, but few genomic sequences of elite inoculant strains are available. Here we contribute with information on the genomes of two commercial strains that are broadly applied to soybean crops in the tropics. B.

The genome of Anopheles darlingi, the main neotropical malaria vector.

Anopheles darlingi is the principal neotropical malaria vector, responsible for more than a million cases of malaria per year on the American continent. Anopheles darlingi diverged from the African and Asian malaria vectors ∼100 million years ago (mya) and successfully adapted to the New World environment. Here we present an annotated reference A.

Limited vegetative compatibility as a cause of somatic recombination in Trichoderma pseudokoningii.

With the aim of a better characterization of the somatic recombination process in Trichoderma pseudokoningii, a progeny from crossings between T. pseudokoningii strains contrasting for auxotroph markers was characterized by RAPD markers and PFGE (electrophoretic karyotype). Cytological studies of the conidia, conidiogenesis and heterokaryotic colonies were also performed.

Reclassification of Rhizobium tropici type A strains as Rhizobium leucaenae sp. nov.

Rhizobium tropici is a well-studied legume symbiont characterized by high genetic stability of the symbiotic plasmid and tolerance to tropical environmental stresses such as high temperature and low soil pH. However, high phenetic and genetic variabilities among R. tropici strains have been largely reported, with two subgroups, designated type A and B, already defined within the species.

The nodC, nodG, and glgX genes of Rhizobium tropici strain PRF 81.

Rhizobium tropici is a diazotrophic microsymbiont of common bean (Phaseolus vulgaris L.) that encompasses important but still poorly studied tropical strains, and a recent significant contribution to the knowledge of the species was the publication of a genomic draft of strain PRF 81, which revealed several novel genes [Pinto et al. Funct Int Gen 9:263-270, 2009].

Phylogeny and taxonomy of a diverse collection of Bradyrhizobium strains based on multilocus sequence analysis of the 16S rRNA gene, ITS region and glnII, recA, atpD and dnaK genes.

The genus Bradyrhizobium encompasses a variety of bacteria that can live in symbiotic and endophytic associations with legumes and non-legumes, and are characterized by physiological and symbiotic versatility and broad geographical distribution. However, despite indications of great genetic variability within the genus, only eight species have been described, mainly because of the highly conserved nature of the 16S rRNA gene. In this study, 169 strains isolated from 43 different legumes were analysed by rep-PCR with the BOX primer, by sequence analysis of the 16S rRNA gene and the 16S-23S rRNA intergenic transcribed spacer (ITS) and by multilocus sequence analysis (MLSA) of four housekeeping genes, glnII, recA, atpD and dnaK.

Multilocus sequence analysis of Brazilian Rhizobium microsymbionts of common bean (Phaseolus vulgaris L.) reveals unexpected taxonomic diversity.

The diazotrophic bacteria collectively known as "rhizobia" are important for establishing symbiotic N(2)-fixing associations with many legumes. These microbes have been used for over a century as an environmentally beneficial and cost-effective means of ensuring acceptable yields of agricultural legumes. The most widely used phylogenetic marker for identification and classification of rhizobia has been the 16S rRNA gene; however, this marker fails to discriminate some closely related species.

rep-PCR fingerprinting and taxonomy based on the sequencing of the 16S rRNA gene of 54 elite commercial rhizobial strains.

In tropical soils, diversity and biotechnological potential of symbiotic diazotrophic bacteria are high. However, the phylogenetic relationships of prominent strains are still poorly understood. In addition, in countries such as Brazil, despite the broad use of rhizobial inoculants, molecular methods are rarely used in the analysis of strains or determination of inoculant performance.

Genetic differences between Bradyrhizobium japonicum variant strains contrasting in N(2)-fixation efficiency revealed by representational difference analysis.

Two variant strains of Bradyrhizobium japonicum, derived from SEMIA 566, adapted to the stressful environmental conditions of the Brazilian Cerrados and characterized by contrasting capacities for N(2) fixation, were compared by representational difference analysis (RDA). Twenty-four gene sequences that are unique to the highly effective strain S 370 were identified, eight showing high similarity to known genes, nine encoding putative proteins and seven representing conserved hypothetical or hypothetical proteins; they were classified in eight functional categories. Among those genes, some were highlighted for their known or potential functions in plant-microbe interactions.

Evidence of horizontal transfer of symbiotic genes from a Bradyrhizobium japonicum inoculant strain to indigenous diazotrophs Sinorhizobium (Ensifer) fredii and Bradyrhizobium elkanii in a Brazilian Savannah soil.

The importance of horizontal gene transfer (HGT) in the evolution and speciation of bacteria has been emphasized; however, most studies have focused on genes clustered in pathogenesis and very few on symbiosis islands. Both soybean (Glycine max [L.] Merrill) and compatible Bradyrhizobium japonicum and Bradyrhizobium elkanii strains are exotic to Brazil and have been massively introduced in the country since the early 1960s, occupying today about 45% of the cropped land.

Variability in Bradyrhizobium japonicum and B. elkanii seven years after introduction of both the exotic microsymbiont and the soybean host in a cerrados soil.

The plasticity of rhizobial genomes is far greater than previously thought, with complex genomic recombination events that may be accelerated by the often stressful environmental conditions of the tropics. This study aimed at evaluating changes in soybean rhizobia due to adaptation to inhospitable environmental conditions (high temperatures, drought, and acid soils) in the Brazilian Cerrados. Both the host plant and combinations of four strains of soybean Bradyrhizobium were introduced in an uncropped soil devoid of rhizobia capable of nodulating soybean.