Genetic diversity of symbiotic bacteria nodulating common bean (Phaseolus vulgaris) in western Kenya (original) (raw)
Related papers
Common bean (Phaseolus vulgaris L.) is a legume that has been reported as highly promiscuous in nodulating with a variety of rhizobial strains, often with low effectiveness in fixing nitrogen. The aim of this work was to assess the symbiotic efficiency of rhizobial strains isolated from common bean seeds, nodules of Arachis hypogaea, Mucuna pruriens, and soils from various Brazilian agroecosystems, followed by the characterization of elite strains identified in the first screening. Forty-five elite strains were analyzed for symbiotic properties (nodulation, plant-growth, and nitrogen-fixation parameters) under greenhouse conditions in pots containing non-sterile soil, and variation in symbiotic performance was observed. Elite strains were also characterized in relation to morphophysiological properties, genetic profiles of reppolymerase chain reaction (PCR; BOX), and restriction fragment length polymorphism (RFLP)-PCR of the 16S rRNA. Sequence analyses of the 16S rRNA were obtained for 17 strains representative of the main groups resulting from all previous analyses. One of the most effective strains, IPR-Pv 2604, was clustered with Rhizobium tropici, whereas strain IPR-Pv 583, showing lower effectiveness in fixing N 2 , was clustered with Herbaspirillum lusitanum. Surprisingly, effective strains were clustered with unusual symbiotic genera/species, including Leifsonia xyli, Stenotrophomonas maltophilia, Burkholderia, and Enterobacter. Some strains recognized in this study were outstanding in their nitrogen-fixing capacity and therefore, show high biotechnological potential for use in commercial inoculants.
2012
Common bean (Phaseolus vulgaris L.) is a legume that has been reported as highly promiscuous in nodulating with a variety of rhizobial strains, often with low effectiveness in fixing nitrogen. The aim of this work was to assess the symbiotic efficiency of rhizobial strains isolated from common bean seeds, nodules of Arachis hypogaea, Mucuna pruriens, and soils from various Brazilian agroecosystems, followed by the characterization of elite strains identified in the first screening. Forty-five elite strains were analyzed for symbiotic properties (nodulation, plant-growth, and nitrogen-fixation parameters) under greenhouse conditions in pots containing non-sterile soil, and variation in symbiotic performance was observed. Elite strains were also characterized in relation to morphophysiological properties, genetic profiles of reppolymerase chain reaction (PCR; BOX), and restriction fragment length polymorphism (RFLP)-PCR of the 16S rRNA. Sequence analyses of the 16S rRNA were obtained for 17 strains representative of the main groups resulting from all previous analyses. One of the most effective strains, IPR-Pv 2604, was clustered with Rhizobium tropici, whereas strain IPR-Pv 583, showing lower effectiveness in fixing N 2 , was clustered with Herbaspirillum lusitanum. Surprisingly, effective strains were clustered with unusual symbiotic genera/species, including Leifsonia xyli, Stenotrophomonas maltophilia, Burkholderia, and Enterobacter. Some strains recognized in this study were outstanding in their nitrogen-fixing capacity and therefore, show high biotechnological potential for use in commercial inoculants.
Acta Agriculturae Scandinavica, Section B — Soil & Plant Science, 2020
Bacteria were isolated from the root nodules using common bean as a trap host. Growth and morphological characteristics of the bacterial isolates were described on yeast extract mannitol mineral salts agar and broth media. The results showed that over 67% of the isolates produced extracellular polysaccharide with an entire margin and convex elevation. The others differentiated into cream yellow, cream white and milky white colouration with colony area ranging from 0.8 to 26 mm 2. The population levels of bacteria nodulating common bean varied in soils and were not affected by the cropping system. However, selected soil parameters greatly influenced the occurrence and distribution of these bacteria. The isolation of indigenous bacteria in all the soils with different cropping systems is an indication that the soils are favourable for nitrogen fixation. Based on the differences in cultural characteristics of the isolates, our data demonstrate the presence of high diversity of bacteria associated with bean nodules.
2016
Plant growth-promoting Rhizobacteria are beneficial native soil bacteria that colonize plant roots and result in increased plant growth. Those that colonise the nodules of legumes are known as nodule associated bacteria. The aim of this study was to determine the effect of chemical soil factors on the abundance of nodule associated bacteria and the symbiotic efficiency of these bacteria when coinoculated with Phaseolus vulgaris in Western Kenya soils. The soil samples were collected from cultivated lands in Kisumu near Lake Victoria, slopes of Mt. Elgon and Kakamega. In each of these regions, the soil samples were collected from four regions. 1ml of soil solution at 10 fold dilution for seven dilution steps (10 -1 to 10 -7 ) and three replications for each dilution was used to inoculate common bean seedling in the Leonard jars. They were harvested after four weeks to determine abundance of nodule associated bacteria using most probable number plant infection method. Mt. Elgon region...
Genomic studies of nitrogen-fixing rhizobial strains from Phaseolus vulgaris seeds and nodules
BMC genomics, 2016
Rhizobia are soil bacteria that establish symbiotic relationships with legumes and fix nitrogen in root nodules. We recently reported that several nitrogen-fixing rhizobial strains, belonging to Rhizobium phaseoli, R. trifolii, R. grahamii and Sinorhizobium americanum, were able to colonize Phaseolus vulgaris (common bean) seeds. To gain further insight into the traits that support this ability, we analyzed the genomic sequences and proteomes of R. phaseoli (CCGM1) and S. americanum (CCGM7) strains from seeds and compared them with those of the closely related strains CIAT652 and CFNEI73, respectively, isolated only from nodules. In a fine structural study of the S. americanum genomes, the chromosomes, megaplasmids and symbiotic plasmids were highly conserved and syntenic, with the exception of the smaller plasmid, which appeared unrelated. The symbiotic tract of CCGM7 appeared more disperse, possibly due to the action of transposases. The chromosomes of seed strains had less transp...
Biological nitrogen fixation by Phaseolus vulgaris
Revista de Ciências Agrárias, 2016
Phaseolus vulgaris L. (common bean) is considered a promiscuous legume in its association with rhizobia since it can be nodulated by several species of the Rhizobiaceae family. In a field experiment in Oeiras (Portugal), strains were isolated from the root nodules of P. vulgaris 675. Each strain was inoculated in two P. vulgaris landraces: Pv 648 and Pv 675. Phylogeny of 16S rRNA, recA and nodC genes were inferred, using partial gene sequences. The results of plant inoculation assays have shown that only one of the isolated strains could successfully nodulate at least the P. vulgaris landrace (Pv 675), with an index of effectiveness of 31%. This strain was identified as belonging to Rhizobium sullae species by the 16S rRNA and recA genes but it also has a nodC gene from Rhizobium gallicum. The remaining strains were identified as belonging to R. gallicum, Agrobacterium tumefaciens and A. arsenijevicii.
Applied Soil Ecology, 2002
The genetic diversity and the N 2 fixation potential of 10 rhizobial isolates nodulating Phaseolus vulgaris in the soils of the Jordan valley was investigated. Random amplified polymorphic DNA (RAPD) analysis showed that isolates consisted of two major genetic groups and revealed a low level of diversity among the isolates. Significant differences existed in the symbiotic potential of the isolates examined. Only three of the isolates (JOV1, JOV3 and JOV10) possessed promising symbiotic efficiency in terms of shoot dry matter and percent N 2 fixed. Among these, isolate JOV1 had the highest N 2 fixing potential and exhibited a high degree of survival under saline conditions. These results suggest that isolate JOV1 may be considered a potential inoculum for bean in the saline soils of the Jordan valley.
World Journal of Microbiology and Biotechnology, 2008
A greenhouse experiment was performed to evaluate the effects of plant growth-promoting rhizobacteria (PGPR) on nodulation, biological nitrogen fixation (BNF) and growth of the common bean (Phaseolus vulgaris L. cv. Tenderlake). Single and dual inoculation treatments of bean with Rhizobium and/or PGPR were administered to detect possible changes in the levels of and interactions between the phytohormones IAA and cytokinin. Bean plants cv. Tenderlake were grown in pots containing Fluvic Neosol eutrophic (pH 6.5). Fourteen kilogram aliquots of soil contained in 15-l pots were autoclaved. Bean seeds were surface sterilized and inoculated with Rhizobium tropici (CIAT 899-standard strain) alone and in combination with one of the PGPR strains: Bacillus endophyticus (DSM 13796), B. pumilus (DSM 27), B. subtilis (DSM 704), Paenibacillus lautus (DSM 13411), P. macerans (DSM 24), P. polymyxa (DSM 36), P. polymyxa (Loutit L.) or Bacillus sp.(65E180). The experimental design was randomized block design with three replications. Beans co-inoculated with Rhizobium tropici (CIAT899) and Paenibacillus polymyxa (DSM 36) had higher leghemoglobin concentrations, nitrogenase activity and N 2 fixation efficiency and thereby formed associations of greater symbiotic efficiency. Inoculation with Rhizobium and P. polymyxa strain Loutit (L) stimulated nodulation as well as nitrogen fixation. PGPR also stimulated specific-nodulation (number of nodules per gram of root dry weight) increases that translated into higher levels of accumulated nitrogen. The activities of phytohormones depended on their content and interactions with Rhizobium tropici and Paenibacillus and/or Bacillus (PGPR) strains which affect the cytokinin in content in the common bean.
Biocatalysis and agricultural biotechnology, 2019
Rhizobia are soil bacteria known for their ability to nodulate and fix nitrogen with legumes. Some rhizobia also show different plant growth promoting characteristics (PGP); they can therefore be used as effective biofertilizers. Phaseolus vulgaris is considered a weak nitrogen fixer; therefore, screening experiments have been designed to select stress-tolerant effective bean rhizobia that have also PGP traits. Surveys of common bean fields in Morocco lead to the isolation of 113 bacteria inhabiting root nodules. Screening tests showed that 45 isolates exhibited positive phosphate solubilization, and auxin and siderophores production as well as high salt and pH tolerance. Correspondence analysis showed that salt tolerance and phosphate solubilization were origin related. Among the screened isolates, 18 were able to renodulate common bean but only 3 were highly effective with their host plant. Interestingly, phylogenetic analysis of 16S rRNA gene showed that the nodulating isolates clustering within the Rhizobium genus were represented by only two isolates related to R. miluonense and R. yanglingense while the remaining strains belonged to the Agrobacterium genus. Our results revealed also the coexistence of several endophytic bacteria with the symbiotic strains inside the nodules. These bacteria are stress tolerant and possess potential PGP traits, which indicate that they could stimulate common bean growth and contribute to N and P plants nutrition.