Abstract
Lupinus albescens is a resistant cover plant that establishes symbiotic relationships with bacteria belonging to the Bradyrhizobium genus. This symbiosis helps the development of these plants in adverse environmental conditions, such as the ones found in arenized areas of Southern Brazil. This work studied three Bradyrhizobium sp. (AS23, NAS80 and NAS96) isolated from L. albescens plants that grow in extremely poor soils (arenized areas and adjacent grasslands). The genomes of these three strains were sequenced in the Ion Torrent platform using the IonXpress library preparation kit, and presented a total number of bases of 1,230,460,823 for AS23, 1,320,104,022 for NAS80, and 1,236,105,093 for NAS96. The genome comparison with closest strains Bradyrhizobium japonicum USDA6 and Bradyrhizobium diazoefficiens USDA110 showed important variable regions (with less than 80% of similarity). Genes encoding for factors for resistance/tolerance to heavy metal, flagellar motility, response to osmotic and oxidative stresses, heat shock proteins (present only in the three sequenced genomes) could be responsible for the ability of these microorganisms to survive in inhospitable environments. Knowledge about these genomes will provide a foundation for future development of an inoculant bioproduct that should optimize the recovery of degraded soils using cover crops.
Highlights
Lupinus albescens is a leguminous plant native of Uruguay, Paraguay, Northwestern Argentina, and Southern Brazil (Wolko et al, 2011)
Its symbiosis with nitrogen fixing bacteria belonging to the Bradyrhizobium genus helps the growth and development of this plant in adverse environmental conditions, such as drought, salt excess, and heavy metal contamination
A phylogenetic analysis encompassing all Bradyrhizobium reference species showed that isolates AS23 and NAS80 belong to a group where none of the reference species were allocated, while isolate NAS96 grouped with eight Bradyrhizobium reference species
Summary
Lupinus albescens is a leguminous plant native of Uruguay, Paraguay, Northwestern Argentina, and Southern Brazil (Wolko et al, 2011). Regions in southern Brazil present extremely poor soils that are prone to arenization, and the association between L. albescens plants and selected Bradyrhizobium species has been shown to be a good strategy for improving the potential of this plant to recover arenized and degraded sites (Rovedder and Eltz, 2008).
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