Functional relationships between plasmids and their significance for metabolism and symbiotic performance of Rhizobium leguminosarum bv. trifolii

Abstract

Rhizobium leguminosarum bv. trifolii TA1 (RtTA1) is a soil bacterium establishing a highly specific symbiotic relationship with clover, which is based on the exchange of molecular signals between the host plant and the microsymbiont. The RtTA1 genome is large and multipartite, composed of a chromosome and four plasmids, which comprise approximately 65 % and 35 % of the total genome, respectively. Extrachromosomal replicons were previously shown to confer significant metabolic versatility to bacteria, which is important for their adaptation in the soil and nodulation competitiveness. To investigate the contribution of individual RtTA1 plasmids to the overall cell phenotype, metabolic properties and symbiotic performance, a transposon-based elimination strategy was employed. RtTA1 derivatives cured of pRleTA1b or pRleTA1d and deleted in pRleTA1a were obtained. In contrast to the in silico predictions of pRleTA1b and pRleTA1d, which were described as chromid-like replicons, both appeared to be completely curable. On the other hand, for pRleTA1a (symbiotic plasmid) and pRleTA1c, which were proposed to be unessential for RtTA1 viability, it was not possible to eliminate them at all (pRleTA1c) or entirely (pRleTA1a). Analyses of the phenotypic traits of the RtTA1 derivatives obtained revealed the functional significance of individual plasmids and their indispensability for growth, certain metabolic pathways, production of surface polysaccharides, autoaggregation, biofilm formation, motility and symbiotic performance. Moreover, the results allow us to suggest broad functional cooperation among the plasmids in shaping the phenotypic properties and symbiotic capabilities of rhizobia.Electronic supplementary materialThe online version of this article (doi:10.1007/s13353-014-0220-2) contains supplementary material, which is available to authorized users.

Native plasmids restrict growth of Phaeobacter inhibens DSM 17395: Energetic costs of plasmids assessed by quantitative physiological analyses

“…parent strains (e.g. Bergsveinson et al, 2014;Brom et al, 1992;di Cenzo et al, 2014;Dziewit et al, 2014;Oresnik et al, 2000;Stasiak et al, 2014). The present study provides the first quantitative-stoichiometric analysis of plasmid costs.…”

“…Curing of native ECRs from different bacteria resulted in similar or diminished growth performances (evaluated from μ and OD max only, with complex and/or defined mineral media) of the mutants compared to the ECR carrying parent strains (e.g. Bergsveinson et al ., ; Brom et al ., ; di Cenzo et al ., ; Dziewit et al ., ; Oresnik et al ., ; Stasiak et al ., ). The present study provides the first quantitative–stoichiometric analysis of plasmid costs.…”

Multi-disciplinary approaches for studying rhizobium – legume symbioses

“…The influence of soil properties, plant host, and other biotic 260 factors including microbial communities, bacteriophages, plasmids, and other invasive DNA 261 elements all surely play a role in the generation of rhizobial diversity (Bromfield et al 1987, 262 Harrison et al 1989, Carelli et al 2000, Silva et al 2007, Talebi et al 2008, Toro et al 2018. to the symbiotic process, revealing that key symbiotic genes can be located on megaplasmids, that 277 optimal symbiotic performance often requires more than one megaplasmid, and that megaplasmids 278 can carry loci required for effective competition for nodule occupancy (Barbour and Elkan 1989, 279 Hynes and McGregor 1990, Baldani et al 1992, Brom et al 1992, Hu et al 2007, Barreto et al 280 2012, Stasiak et al 2014. In contrast, some rhizobial plasmids impair symbiotic development.…”

Multidisciplinary approaches for studying rhizobium–legume symbioses

“…[Colour online. ] larly, genome reduction studies have highlighted the importance of megaplasmids and chromids to the symbiotic process, revealing that key symbiotic genes can be located on megaplasmids, that optimal symbiotic performance often requires more than one megaplasmid, and that megaplasmids can carry loci required for effective competition for nodule occupancy (Barbour and Elkan 1989;Hynes and McGregor 1990;Baldani et al 1992;Brom et al 1992;Hu et al 2007;Barreto et al 2012;Stasiak et al 2014). In contrast, some rhizobial plasmids impair symbiotic development.…”