A Genomotaxonomy View of the Bradyrhizobium Genus

Abstract

Whole genome analysis of the Bradyrhizobium genus using average nucleotide identity (ANI) and phylogenomics showed the genus to be essentially monophyletic with seven robust groups within this taxon that includes nitrogen-fixing nodule forming bacteria as well as free living strains. Despite the wide genetic diversity of these bacteria no indication was found to suggest that the Bradyrhizobium genus have to split in different taxa. Bradyrhizobia have larger genomes than other genera of the Bradyrhizobiaceae family, probably reflecting their metabolic diversity and different lifestyles. Few plasmids in the sequenced strains were revealed from rep gene analysis and a relatively low proportion of the genome is devoted to mobile genetic elements. Sequence diversity of recA and glnII gene metadata was used to theoretically estimate the number of existing species and to predict how many would exist. There may be many more species than those presently described with predictions of around 800 species in nature. Different arguments are presented suggesting that nodulation might have arose in the ancestral genus Bradyrhizobium .

Long-term monoculture reduces the symbiotic rhizobial biodiversity of peanut

“…2 and Fig. S6) as Bradyrhizobium spp., which is consistent with the results of previous studies on peanut rhizobia isolated from China and Argentina [3,29,31]. The identification of most of the isolates into genospecies corresponding to B. liaoningense, B. arachidis, B. guangdongense and B. yuanmingense demonstrated that these species are common peanut rhizobia in China and in other countries [3,6,14,23,28,29,38,42].…”

“…I identified in the present study were newly recorded as peanut rhizobia and their biogeographic distribution was first reported here. These results demonstrated that (1) the main peanut rhizobia are restricted to the Bradyrhizobium species, which belong to the B. japonicum supergroup or superclade, which was classified recently [1,31]; (2) the peanut nodulating bradyrhizobia have been diversifying in different regions under the selection of soil conditions; and (3) the community structure of peanut bradyrhizobia is also shaped by the monoculture history, competitive ability, and soil properties.…”

“…It has been reported that peanut mainly forms symbiosis with different slow-growing rhizobia classified as Bradyrhizobium [2,8,28,31,38]. In addition to the 14 new candidate Bradyrhizohttps://doi.org/10.1016/j.syapm.2020.126101 0723-2020/© 2020 Elsevier GmbH.…”

Diversity, Phylogeny and Plant Growth Promotion Traits of Nodule Associated Bacteria Isolated from Lotus parviflorus

“…), and L. uliginosus have been shown to be nodulated by closely related bradyrhizobia that are in the same cross-inoculation group [9,16,17]. The genus Bradyrhizobium comprises highly diversified bacteria, with 39 described species thus far [18][19][20], including some photosynthetic strains [21][22][23]. The 16S rRNA gene is very conserved within this genus and, like the symbiotic genes, has been shown to be laterally transmitted [24,25].…”

Bradyrhizobia associated with Laburnum anagyroides, an exotic legume grown in Poland

“…Bradyrhizobium communities are also abundant in many soils where legumes are absent, often acting as endophytes of different plants (Vanlnsberghe et al 2015). The studies have revealed that the genus Bradyrhizobium is separated into seven lineages, including symbiotic as well non-symbiotic bacteria (Avontuur et al 2019;Ormeño-Orrillo and Martínez-Romero 2019). A large number of species in Bradyrhizobium has been recognized, however the list of species in this genus will probably be still growing due to the rapid development of molecular tools and the huge diversity of this genus (Stępkowski et al 2018;de Lajudie et al 2019).…”