Characterization of rhizobia isolates obtained from nodules of wild genotypes of common bean

Abstract

This study aimed to evaluate the tolerance to salinity and temperature, the genetic diversity and the symbiotic efficiency of rhizobia isolates obtained from wild genotypes of common bean cultivated in soil samples from the States of Goiás, Minas Gerais and Paraná. The isolates were subjected to different NaCl concentrations (0%, 1%, 2%, 4% and 6%) at different temperatures (28 °C, 33 °C, 38 °C, 43 °C and 48 °C). Genotypic characterization was performed based on BOX-PCR, REP-PCR markers and 16S rRNA sequencing. An evaluation of symbiotic efficiency was carried out under greenhouse conditions in autoclaved Leonard jars. Among 98 isolates about 45% of them and Rhizobium freirei PRF81 showed a high tolerance to temperature, while 24 isolates and Rhizobium tropici CIAT899 were able to use all of the carbon sources studied. Clustering analysis based on the ability to use carbon sources and on the tolerance to salinity and temperature grouped 49 isolates, R. tropici CIAT899 and R. tropici H12 with a similarity level of 76%. Based on genotypic characterization, 65% of the isolates showed an approximately 66% similarity with R. tropici CIAT899 and R. tropici H12. About 20% of the isolates showed symbiotic efficiency similar to or better than the best Rhizobium reference strain (R. tropici CIAT899). Phylogenetic analysis of the 16S rRNA revealed that two efficient isolates (ALSG5A1 and JPrG6A8) belong to the group of strains used as commercial inoculant for common bean in Brazil and must be assayed in field experiments.

Genetic and phenotypic diversity of Rhizobium isolates from Southern Ecuador

“…Surprisingly, 11 isolated strains did not affect the N content in plants, having no significant difference with the control, demonstrating that only some Rhizobium-Mantequilla interactions can produce an efficient symbiosis. Similar results were observed by Cardoso et al (2017), who identified several native Rhizobium strains that stimulated nodule dry weight in common beans, but most of them were unable to produce a positive effect on total N content. In this study, more than half of the strains fixed less N than the control treatment without inoculation, and approximately 20% of isolates showed a symbiotic efficiency similar to or better than the best Rhizobium reference strain CIAT899.…”

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

“…The bacterial strains analyzed here are rhizobia obtained from nodules of L. anagyroides growing in Poland. To get a tentative insight into the genetic diversity of the isolates we performed rep-PCR fingerprinting with the BOX A1R primer, which had been shown to be a reliable typing method used for differentiation and preliminary characterization of rhizobial strain collections (Koeuth et al 1995;Kaschuk et al 2006;Menna et al 2009;Cardoso et al 2017). The BOX-PCR analysis provided the basis for separating the isolates into three distinct groups (Fig.…”

Inoculation of rhizobia increases lima bean (Phaseolus lunatus) yield in soils from Piauí and Ceará states, Brazil

“…The responses of plants to BNF varies according to the rhizobia (Cardoso et al, 2017) and their growing region (Leggett et al, 2017). Thus, rhizobia isolated from a region and adapted to its specific soil conditions need to be evaluated in different locations and conditions, such as temperature, chemical properties and population of native bacteria (Koskey et al, 2017;Irisarri et al, 2019).…”