The fact that pRet42a transfer is also decreased in a derivative lacking

the pSym of GR64 (GR64-5), points to a chromosomal location of the putative inhibitor locus. Similarly, S. fredii pSfr64a was unable to perform conjugative transfer or induce transfer of pSfr64b in R. etli genomic background (CFN2001-3). Only R. etli pRet42a was still able to induce pSfr64b transfer in the R. etli background (CFN2001-2). The pSym of GR64 differs from the typical R. etli pSym To further analyze the bean-nodulating S. fredii strain GR64, we performed a phylogenetic analysis with chromosomal genes (recA, rpoB), and with the plasmid-encoded genes nifH and repB. The results (Figure 4) show that, based on the phylogeny of the chromosomal genes, GR64 clusters within the fredii clade, while nifH

this website and repB genes group strain GR64 with other bean-nodulating Sinorhizobium strains isolated from the South of Spain (Granada and Sevilla) [22, 23] and from the North of S3I-201 mw Africa (Tunisia) [24] (Figure 4C). The data obtained indicate that GR64 has a S. fredii chromosome but carries a pSym that allows nodulation of Phaseolus. However, this plasmid differs from typical R. etli pSyms in its replication genes, allowing it to coexist with plasmid pSfr64a, which does share its replication genes with the R. etli pSym. Another feature JQ1 in vitro that differentiates this pSym is the presence of a single copy of the nifH gene. Figure 4 Phylogeny of ROS1 S. fredii GR64. Maximum likelihood phylogenetic trees based on chromosomal: (A) recA, (B) rpoB, and plasmid: (C) nifH and (D) repB gene fragments. Arrows indicate the localization of S. fredii GR64, and R.etli CFN42. Discussion Genomic comparisons of S. meliloti, A. tumefaciens, and R. etli [25], and between Rhizobium

leguminosarum bv viciae and Rhizobium etli [26], have shown that chromosomes are well conserved both in gene content and gene order, whereas plasmids presented few common regions and lacked synteny, except for some pairs of plasmids whose features indicate that they were part of the ancestral genome, and may be considered as secondary chromosomes [26, 27]. In R. etli, the symbiotic and self-transmissible plasmids are the less conserved replicons [25] with fewer collinear blocks [26]. In this paper we show that a conjugative plasmid from a bean nodulating S. fredii strain is formed by large segments of replicons found in strains belonging to different species from diverse geographic origins. These replicons include two plasmids of R. etli, and a S. fredii chromosome. In GR64, bean-nodulation is provided by pSfr64b. Although the phylogenetic relationship of the GR64 nifH gene shows that it is closely related to the R. etli gene (Figure 4), pSfr64b differs from the typical R. etli pSym in other features (see above). We have previously reported that R.