European Origin of Bradyrhizobium Populations Infecting Lupins and Serradella in Soils of Western Australia and South Africa

Abstract

We applied a multilocus phylogenetic approach to elucidate the origin of serradella and lupin Bradyrhizobium strains that persist in soils of Western Australia and South Africa. The selected strains belonged to different randomly amplified polymorphic DNA (RAPD)-PCR clusters that were distinct from RAPD clusters of applied inoculant strains. Phylogenetic analyses were performed with nodulation genes (nodA, nodZ, nolL, noeI), housekeeping genes (dnaK, recA, glnII, atpD), and 16S-23S rRNA intergenic transcribed spacer sequences. Housekeeping gene phylogenies revealed that all serradella and Lupinus cosentinii isolates from Western Australia and three of five South African narrow-leaf lupin strains were intermingled with the strains of Bradyrhizobium canariense, forming a well supported branch on each of the trees. All nodA gene sequences of the lupin and serradella bradyrhizobia formed a single branch, referred to as clade II, together with the sequences of other lupin and serradella strains. Similar patterns were detected in nodZ and nolL trees. In contrast, nodA sequences of the strains isolated from native Australian legumes formed either a new branch called clade IV or belonged to clade I or III, whereas their nonsymbiotic genes grouped outside the B. canariense branch. These data suggest that the lupin and serradella strains, including the strains from uncultivated L. cosentinii plants, are descendants of strains that most likely were brought from Europe accidentally with lupin and serradella seeds. The observed dominance of B. canariense strains may be related to this species' adaptation to acid soils common in Western Australia and South Africa and, presumably, to their intrinsic ability to compete for nodulation of lupins and serradella.

Multilocus Sequence Analysis of Root Nodule Bacteria Associated with <i>Lupinus</i> spp. and <i>Glycine max</i>

“…According to the phylogeny of the concatenated dataset, we propose that USDA strains 3063, 3717, 3043 and 3057a should be considered for reclassification. Also, despite evidence that lupines are mainly nodulated by members of the genus Bradyrhizobium [3], the two strains isolated from lupines in this study were shown to be Burkholderia sp. and Rhizobium sp.…”

Bradyrhizobium iriomotensesp. nov., Isolated from a Tumor-Like Root of the LegumeEntada koshunensisfrom Iriomote Island in Japan

“…Topological incongruence among the phylogenetic trees of different marker genes of a single strain is not uncommon, 48,49,54) and such incongruence of topologies based on GlnII and RecA of bradyrhizobial strains have also been reported by other authors. 9) In the GyrB-tree (Fig.…”

Rhizobial communities in symbiosis with legumes: genetic diversity, competition and interactions with host plants

“…Moreover, frequent genetic transfer and recombination events were evidenced within species (between sublineages) in different models [11,36,42,43,49,101]. There is an agreement, that (a) in numerous cases the world distribution of microsymbiont strains followed the distribution of their hosts, and the symbiosis-associated part of the genome (localized on symbiotic plasmid or symbiotic island) was subjected to the most intense evolution and fitting [103,104,106,107], and (b) other (non-symbiotic) parts of the rhizobial genome changed together with the symbiosis-related regions [105,108]. Genetic analyses of microsymbiont populations isolated from different but closely related legumes support the hypothesis of coevolution in Rhizobium-legume symbiosis, which takes place in centers of genetic diversification of plant hosts [109][110][111].…”