Rhizobium azibense sp. nov., a nitrogen fixing bacterium isolated from root-nodules of Phaseolus vulgaris

Cao

Systematic and Applied Microbiology

et al. 2016

The biodiversity and biogeography of rhizobia associated with bean in Shaanxi Province were investigated. A total of 194 bacterial isolates from bean nodules collected from 13 sampling sites were characterized based on phylogenetic analyses of the 16S rRNA gene, the housekeeping genes recA, glnII and atpD, and the symbiotic genes nodC and nifH. Fifteen genospecies belonging to the genera Rhizobium, Agrobacterium, Ensifer, Bradyrhizobium and Ochrobactrum were defined among the isolates, with Rhizobium sp. II, Agrobacterium sp. II, E. fredii and R. phaseoli being the dominant groups. Four symbiotic gene lineages corresponding to Rhizobium sp. I, Rhizobium sp. II, R. phaseoli and B. liaoningense were detected in the nodC and nifH sequence analyses, indicating different origins for the symbiotic genes and their co-evolution with the chromosome of the bacteria. Moreover, the Ensifer isolates harbored symbiotic genes closely related to bean-nodulating Pararhizobium giardinii, indicating possible lateral gene transfer from Rhizobium to Ensifer. Correlation of rhizobial community composition with moisture, temperature, intercropping, soil features and nutrients were detected. All the results demonstrated a great diversity of bean rhizobia in Shaanxi that might be due to the adaptable evolution of the bean-nodulating rhizobia subjected to the diverse ecological conditions in the area.

“…lusitanum [40], R. phaseoli [34], R. azibense [30], R. freirei [9], Ensifer meliloti [55], E. americanum [31], and Bradyrhizobium sp. [17], among others.…”

Section: Introductionmentioning

confidence: 99%

Biodiversity and biogeography of rhizobia associated with common bean (Phaseolus vulgaris L.) in Shaanxi Province

Cao

Systematic and Applied Microbiology

et al. 2016

Systematic and Applied Microbiology

“…It has been cultivated worldwide as a grain or vegetable crop, and forms root nodules in different regions with a wide range of symbiotic nitrogen-fixing bacteria, including the Rhizobium species R. etli, R. gallicum, R. giardinii, R. leguminosarum, R. lusitanum, R. phaseoli, R. vallis, R. leucaenae [36], R. tropici [4], R. mesoamericanum [25], R. freirei [11] and R. azibense [29], as well as Ensifer meliloti [50], Ensifer americanum [30], and Bradyrhizobium sp. [17].…”

Section: Introductionmentioning

confidence: 99%

Microsymbionts of Phaseolus vulgaris in acid and alkaline soils of Mexico

Verástegui-Valdés

Zhang

Rivera-Orduña

et al. 2014

In order to investigate bean-nodulating rhizobia in different types of soil, 41 nodule isolates from acid and alkaline soils in Mexico were characterized. Based upon the phylogenetic studies of 16S rRNA, atpD, glnII, recA, rpoB, gyrB, nifH and nodC genes, the isolates originating from acid soils were identified as the phaseoli symbiovar of the Rhizobium leguminosarum-like group and Rhizobium grahamii, whereas the isolates from alkaline soils were defined as Ensifer americanum sv. mediterranense and Rhizobium radiobacter. The isolates of “R. leguminosarum” and E. americanum harbored nodC and nifH genes, but the symbiotic genes were not detected in the four isolates of the other two species. It was the first time that “R. leguminosarum” and E. americanum have been reported as bean-nodulating bacteria in Mexico. The high similarity of symbiotic genes in the Rhizobium and Ensifer populations showed that these genes had the same origin and have diversified recently in different rhizobial species. Phenotypic characterization revealed that the “R. leguminosarum” population was more adapted to the acid and low salinity conditions, while the E. americanum population preferred alkaline conditions. The findings of this study have improved the knowledge of the diversity, geographic distribution and evolution of bean-nodulating rhizobia in Mexico.

Food Technol. Biotechnol.

“…Compared to other legumes, common bean can form symbiotic relations with a number of species mostly belonging to the genus Rhizobium (2)(3)(4). Despite the great symbiotic potential of common bean, in comparison with other legumes, it fi xes considerably small amounts of atmospheric nitrogen (5).…”

mentioning

confidence: 99%

Genetic Diversity and Symbiotic Efficiency of Indigenous Common Bean Rhizobia in Croatia

Pohajda¹,

Babić

Rajnović

et al. 2016

Natural process of symbiotic nitrogen fi xation has a unique role in a sustainable legume production. Nodule bacteria, collectively named rhizobia, in symbiotic associations with legumes enable considerable entries of biologically fi xed nitrogen into ecosystems. In order to maxi- SummaryNodule bacteria (rhizobia) in symbiotic associations with legumes enable considerable entries of biologically fi xed nitrogen into soil. Eff orts are therefore made to intensify the natural process of symbiotic nitrogen fi xation by legume inoculation. Studies of fi eld populations of rhizobia open up the possibility to preserve and probably exploit some indigenous strains with hidden symbiotic or ecological potentials. The main aim of the present study is to determine genetic diversity of common bean rhizobia isolated from diff erent fi eld sites in central Croatia and to evaluate their symbiotic effi ciency and compatibility with host plants. The isolation procedure revealed that most soil samples contained no indigenous common bean rhizobia. The results indicate that the cropping history had a signifi cant impact on the presence of indigenous strains. Although all isolates were found to belong to species Rhizobium leguminosarum, signifi cant genetic diversity at the strain level was determined. Application of both random amplifi cation of polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC--PCR) methods resulted in similar grouping of strains. Symbiotic effi ciency of indigenous rhizobia as well as their compatibility with two commonly grown bean varieties were tested in fi eld experiments. Application of indigenous rhizobial strains as inoculants resulted in signifi cantly diff erent values of nodulation, seed yield as well as plant nitrogen and seed protein contents. The most abundant nodulation and the highest plant nitrogen and protein contents were determined in plants inoculated with R. leguminosarum strains S 17/2 and S 21/6 . Although, in general, the inoculation had a positive impact on seed yield, diff erences depending on the applied strain were not determined. The overall results show the high degree of symbiotic effi ciency of the specifi c indigenous strain S 21/6 . These results indicate diff erent symbiotic potential of indigenous strains and confi rmed the importance of rhizobial strain selection. These are the fi rst studies of indigenous common bean rhizobia in Croatia that provide the basis for further characterization and selection of highly effi cient indigenous strains and their potential use in agricultural practice and future research.