Novel Cupriavidus Strains Isolated from Root Nodules of Native Uruguayan Mimosa Species

Abstract

The large legume genus Mimosa is known to be associated with both alphaproteobacterial and betaproteobacterial symbionts, depending on environment and plant taxonomy, e.g., Brazilian species are preferentially nodulated by Burkholderia, whereas those in Mexico are associated with alphaproteobacterial symbionts. Little is known, however, about the symbiotic preferences of Mimosa spp. at the southern subtropical limits of the genus. In the present study, rhizobia were isolated from field-collected nodules from Mimosa species that are native to a region in southern Uruguay. Phylogenetic analyses of sequences of the 16S rRNA, recA, and gyrB core genome and the nifH and nodA symbiosis-essential loci confirmed that all the isolates belonged to the genus Cupriavidus. However, none were in the well-described symbiotic species C. taiwanensis, but instead they were closely related to other species, such as C. necator, and to species not previously known to be symbiotic (or diazotrophic), such as C. basilensis and C. pinatubonensis. Selection of these novel Cupriavidus symbionts by Uruguayan Mimosa spp. is most likely due to their geographical separation from their Brazilian cousins and to the characteristics of the soils in which they were found. IMPORTANCEWith the aim of exploring the diversity of rhizobia associated with native Mimosa species, symbionts were isolated from root nodules on five Mimosa species that are native to a region in southern Uruguay, Sierra del Abra de Zabaleta. In contrast to data obtained in the major centers of diversification of the genus Mimosa, Brazil and Mexico, where it is mainly associated with Burkholderia and Rhizobium/Ensifer, respectively, the present study has shown that all the isolated symbiotic bacteria belonged to the genus Cupriavidus. Interestingly, none of nodules contained bacteria belonging to the well-described symbiotic species C. taiwanensis, but instead they were related to other Cupriavidus species such as C. necator and C. pinatubonensis. These data suggest the existence of a higher diversity within beta-rhizobial Cupriavidus than was previously suspected, and that Mimosa spp. from Sierra del Abra de Zabaleta, may be natural reservoirs for novel rhizobia.

Soil characteristics determine the rhizobia in association with different species of Mimosa in central Brazil

“…However, since 2001, several reports have demonstrated that members of the βproteobacteria class also nodulate and fix nitrogen in association with these plants (Chen et al 2001;Vandamme et al 2002;Chen et al 2003;Elliott et al 2007aElliott et al , b, 2009Bournaud et al 2013;Liu et al 2014;Lemaire et al 2015). In particular, studies carried out with the pantropical Mimosa genus have been used to demonstrate that bacteria from the β-proteobacteria play a key role in nitrogen fixation in association with leguminous plants (Chen et al 2005a, b;Elliott et al 2009;Gyaneshwar et al 2011;Bontemps et al 2010;Reis Junior et al 2010;Lammel et al 2013;Platero et al 2016). Indeed, Mimosa is now used as a model for studies involving these symbiotic relationships in natural ecosystems.…”

“…In Uruguay, the main symbionts associated with Mimosa belong to the genus Cupriavidus (Platero et al 2016), which is related to Paraburkholderia in the βproteobacteria class. In Mexico, an important center of Mimosa diversity, species of this genus are predominantly associated with α-proteobacteria from the genera Rhizobium and Ensifer (Bontemps et al 2016).…”

Draft Genome Sequence of Cupriavidus UYMMa02A, a Novel Beta-Rhizobium Species

“…Interestingly, Cupriavidus sp. UYMMa02A is not related to the previously described symbiotic species C. taiwanensis or C. necator (11). The symbiotic bacterial isolation technique has been described elsewhere (11).…”

Phylogenetic Analysis of Symbiotic Bacteria Associated with Two <i>Vigna</i> Species under Different Agro-Ecological Conditions in Venezuela

“…Venezuelan Paraburkholderia was identified by biogeographic relationship and soil fertility problems (Artigas et al, 2019). In Latin-American countries, such as Mexico, Brazil, and Uruguay, Burkholderia has mainly been associated with Mimosa species (Bontemps et al, 2016;Platero et al, 2016). Some Burkholderia species have been reported as acid-tolerant and commonly distributed in low nutrient soils (Graham, 1992;De Oliveira-L et al, 2015;Bontemps et al, 2016;Platero et al, 2016;Artigas et al, 2019).…”