Abstract The bacteria called rhizobia are nitrogen-fixing bacteria which establish symbioses with plant species in the legume family. They induce positive interaction between soil microorganisms and the plant and are essential for plant... more
Abstract The bacteria called rhizobia are nitrogen-fixing bacteria which establish symbioses with plant species in the legume family. They induce positive interaction between soil microorganisms and the plant and are essential for plant growth in semiarid Mediterranean ecosystems that usually present severe water stress, scarcity of plants, low available nutrients and microbiological activity. Considered as one of the endemic legume shrubs of the Mediterranean basin, Retama plays an important role in nitrogen cycling, and thus, can be used to restore heavily disturbed and degraded soils. These species are adapted to harsh environmental conditions and their establishment and growth are enhanced by their ability to enter into effective symbiosis with multiple rhizobia species. In this article, we review the cumulative evidence of the Retama-rhizobia symbiosis in the Mediterranean basin and its ecological impact on revegetation and soil fertilization
— A field experiment was conducted in Summer-Spring cropping season 2016 at Cujut district, DakNong province, Vietnam to study the effects of rhizobia and phosphate-solubilizing bacteria (PSB) on soybean (cv. Cujut) cultivated on... more
— A field experiment was conducted in Summer-Spring cropping season 2016 at Cujut district, DakNong province, Vietnam to study the effects of rhizobia and phosphate-solubilizing bacteria (PSB) on soybean (cv. Cujut) cultivated on ferralsols. The experiment consisted of six treatments as follows: control (no fertilizer, no inoculant), 240 kg/ha NPK 15-15-15, rhizobial inoculant [with liquid cover seeds] + 20 kg N/ha applied at 10 days after sowing [DAS], PSB inoculant [with liquid cover seeds] + 20 kg N/ha at 10 DAS, rhizobial and PSB inoculant [with liquid cover seeds] + 400 kg fertilizer/ha + 20 kg N/ha at 10 DAS and endophytic bacteria inoculant [with liquid cover seeds] + 400 kg fertilizer/ha + 20 kg N/ha at 10 DAS from June to August, 2016. The results showed that application of rhizobial inoculant and/or PSB inoculant produced significantly higher yield component, grain yield than control and did not differ from 240 kg/ha NPK 15-15-15. Consequently, application of rhizobia and PSB improved soil fertility after harversting however using mixture of rhizobia and PSB inoculation plus 400 kg biofertilizer/ha +20 kg N/ha for soybean cultivation supported yield component, grain yield and oil, protein in seed than control and equivalent with treatment of chemical fertilizer (240 kg/ha NPK 15-15-15). This technique not only increased grain yield, incomes for farmers but also improved soil fertility.
Rhizobia were isolated from the root nodules of Clitoria ternatea in Thailand. The phylogeny of the isolates was investigated using 16S rDNA and the internal transcribed spacer (ITS) region from 16S to 23S rDNA. The phylogenetic tree of... more
Rhizobia were isolated from the root nodules of Clitoria ternatea in Thailand. The phylogeny of the isolates was investigated using 16S rDNA and the internal transcribed spacer (ITS) region from 16S to 23S rDNA. The phylogenetic tree of the 16S rDNA showed that ten of the eleven isolates belonged to Bradyrhizobium elkanii, and one belonged to Bradyrhizobium japonicum. The topology of the ITS tree was similar to that of 16S rDNA. The acetylene reduction activity was higher for the nodules inoculated with the isolated B. elkanii strains than for those inoculated with B. japonicum strains. When C. ternatea plants were inoculated with various Bradyrhizobium USDA strains isolated from Glycine max, C. ternatea formed many effective nodules with B. elkanii, especially USDA61. However, acetylene reduction activity per plant and the growth were higher in C. ternatea inoculated with our isolates. From these data we propose that effective rhizobia inoculant were identified for C. ternatea cultivation.
—Aiming at accurately and rapidly identifying our heavy metal resistant rhizobial strains, genomic average nucleotide identity (ANI) and core genome analyses were performed to investigate the phylogenetic relationships among 45 strains in... more
—Aiming at accurately and rapidly identifying our heavy metal resistant rhizobial strains, genomic average nucleotide identity (ANI) and core genome analyses were performed to investigate the phylogenetic relationships among 45 strains in the families of Rhizobiaceae and Bradyrhizobiaceae. The results showed that both of the ANI and core-genome phylogenetic trees revealed similar relationship. In ANI analysis, the 90%, 75% and 70% ANI values could be the thresholds for species, genus and family, respectively. Analyzing the genomes using multi-dimensional scaling and scatter plot showed highly consistent with the ANI and core-genome phylogenetic results. With these thresholds, the 45 strains were divided into 24 genomic species within the genera Agrobacterium, Allorhizobium, Bradyrhizobium, Sinorhizobium and a putative novel genus represented by Ag. albertimagni AOL15. The ten arsenite-oxidizing and antimonite tolerant strains were identified as Ag. radiobacter, and two Sinorhizobium genomic species differing from S. fredii. In addition, the description of Pararhizobium is questioned because ANI values greater than 75% were detected between P. giardinii H152T and Sinorhizobium strains. Also, reversion of the species definition for several strains in R. etli and R. leguminosarum was suggested. Our results demonstrate that analyses of ANI and core-genome are rapid and confident methods to identify the rhizobial strains, and it will be also convenient when more genome data are accumulated.
The present study aims to assess the effect of phosphate solubilizing bacteria (PSB) in interaction with native arbuscular mycorrhizal fungi (AMF) and rhizobia on peanut growth cultivated in the Northwest of Morocco. To perform this aim,... more
The present study aims to assess the effect of phosphate solubilizing bacteria (PSB) in interaction with native arbuscular mycorrhizal fungi (AMF) and rhizobia on peanut growth cultivated in the Northwest of Morocco. To perform this aim, seeds were inoculated with 5 PSB strains: PP22, GP70, GR1, PR29, and GR70, and then grown in unsterilized soil collected from peanut fields. Plant harvesting was made after 8 weeks of growth under chamber conditions. The results demonstrated that PSB treatments showed positive effect on mycorrhizal colonization, nodulation and plant growth parameters. The best results were found with Pseudomonas strains, GP70, PP22 and GR1. This study indicates the great potential of some PSB to improve yield and nutrient uptake of peanut plants in the presence of native rhizobia and AMF. They could serve as biofertilizers, minimizing chemical fertilization that is currently used to obtain high yields for peanut agriculture. Keywords: AMF, growth, peanut, PSB, rhizobia
Malgre l’importance des representants du genre Lotus en Algerie, leur statut symbiotique et la nature des Rhizobia qui leurs sont associes sont meconnus. Cette etude portant sur 39 plants de Lotus appartenant a 15 especes nous a permis de... more
Malgre l’importance des representants du genre Lotus en Algerie, leur statut symbiotique et la nature des Rhizobia qui leurs sont associes sont meconnus. Cette etude portant sur 39 plants de Lotus appartenant a 15 especes nous a permis de verifier qu’ils sont tous nodules et fixateurs d’azote et d’isoler a partir de leurs nodules 38 souches de BNL (Bacteries Nodulant les Legumineuses) qui ont ete authentifiees. Le sequencage du gene de l’ARNr 16S de ces 38 souches de Rhizobia montre une predominance de souches du genre Mesorhizobium represente par 10 especes parmi lesquelles M. erdmanii, M. ciceri et M. jarvisii se sont montrees les plus importantes. La nodulation des especes de Lotus examinees est assuree dans une moindre mesure par des souches des genres Bradyrhizobium et Ensifer, tous deux representes par deux especes. Cette etude a permis, d’une part, de reveler la diversite des Rhizobia associes aux Lotus d’Algerie, et d’autre part, de mettre en evidence une faible implication dans la nodulation des ...
forming rod that can exist as a soil saprophyte or as a legume microsymbiont of Mimosa pigra (giant sensitive plant). LMG 23256T was isolated from a nodule recovered from the roots of the M. pigra growing in Anso, Taiwan. LMG 23256T is... more
forming rod that can exist as a soil saprophyte or as a legume microsymbiont of Mimosa pigra (giant sensitive plant). LMG 23256T was isolated from a nodule recovered from the roots of the M. pigra growing in Anso, Taiwan. LMG 23256T is highly effective at fixing nitrogen with M. pigra. Here we describe the features of B. mimosarum strain LMG 23256T, together with genome sequence infor-mation and its annotation. The 8,410,967 bp high-quality-draft genome is arranged into 268 scaf-folds of 270 contigs containing 7,800 protein-coding genes and 85 RNA-only encoding genes, and is one of 100 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.
Chickpea (Cicer arietinum L.), is a multi-functional crop with important role in the diet as affordable protein source and in sustaining soil fertility through nitrogen fixation. However, its productivity in Ethiopia of 1.9 t ha-1 is... more
Chickpea (Cicer arietinum L.), is a multi-functional crop with important role in the diet as affordable protein source and in sustaining soil fertility through nitrogen fixation. However, its productivity in Ethiopia of 1.9 t ha-1 is lower than its potential of 5 t ha-1 under well managed conditions, partly due to soil fertility limitations. Field experiments were conducted to evaluate effectiveness of elite rhizobia strains on productivity of chickpea. Four rhizobial inoculant treatments and one control with three chickpea varieties were used. Inoculated plants had significantly (p<0.05) better performance with most of the symbiotic traits, grain yield and yield related traits than non-inoculated treatments. Shoot nitrogen yield was increased in the range of 13.0 – 31.34% by inoculation with strain ICRE-025 over the two test sites. The highest level of N fixation was achieved in genotype ICC-4918 by inoculation with EAL-029 and ICRE-025. Investigations at both test sites demonst...
Phosphorus use efficiency in common bean (Phaseolus vulgaris L.) as related to compatibility of association among arbuscular mycorrhizal fungi and rhizobia
International audienceMungbean (Vigna radiata L.) has the potential to establish symbiosis with rhizobia that fix atmospheric dinitrogen (N(2)), and arbuscular mycorrhizal fungi (AMF) that improve the uptake of low mobile soil nutrients... more
International audienceMungbean (Vigna radiata L.) has the potential to establish symbiosis with rhizobia that fix atmospheric dinitrogen (N(2)), and arbuscular mycorrhizal fungi (AMF) that improve the uptake of low mobile soil nutrients such as phosphorus. Both rhizobial and mycorrhizal symbioses can benefit plants synergistically. The tripartite symbiosis of mungbean with rhizobia and AMF was assessed in hydroaeroponic culture under sufficient versus deficient P supplies (250 versus 75 mu mol P plant-(1) week(-1)) by comparing the effects of three AMF species on the mycorrhizal root colonization, rhizobial nodulation, and plant growth. Although, Glomus intraradices colonized well the roots of mungbean in sand and hydroaeroponic cultures, Gigaspora rosea only established well under sand culture conditions, and Acaulospora mellea weakly colonized roots under both culture conditions. Though significant differences of mungbean growth were found with different AMF species in sand, only ...
ABSTRACT Thirty-five isolates of rhizobia were picked up fromRetama raetam root nodules growing in arid lands of Tunisia. A genotypic approach including PCR-RFLP of 16S rDNA and 16S–23S rDNA was used to study their diversity and their... more
ABSTRACT Thirty-five isolates of rhizobia were picked up fromRetama raetam root nodules growing in arid lands of Tunisia. A genotypic approach including PCR-RFLP of 16S rDNA and 16S–23S rDNA was used to study their diversity and their relationships with te n reference strains of rhizobia. Four distinct clusters were defined in numerical analysis of RFLP of 16S rDNA, which related at the 78% similarity level to distinct species ofMesorhizobium, Agrobacterium, Rhizobium andSinorhizobium. More greater variability was detected by analysis of Intergenic Spacers 16S–23S rDNA. The results from both methods used in this study, showed that among all newsolates only three were found to be closely related to species of the genusSinorhizobium.
Nitrogen-fixing symbiosis is globally important in ecosystem functioning and agriculture, yet the evolutionary history of nodulation remains the focus of considerable debate. Recent evidence suggesting a single origin of nodulation... more
Nitrogen-fixing symbiosis is globally important in ecosystem functioning and agriculture, yet the evolutionary history of nodulation remains the focus of considerable debate. Recent evidence suggesting a single origin of nodulation followed by massive parallel evolutionary losses raises questions about why a few lineages in the N2-fixing clade retained nodulation and diversified as stable nodulators while most did not. Within legumes, nodulation is restricted to the two most diverse subfamilies, Papilionoideae and Caesalpinioideae, which show stable retention of nodulation across their core clades. We characterize two nodule anatomy types across 128 species in 56 of the 150 genera of the legume subfamily Caesalpinioideae: 1) fixation thread nodules (FTs), where nitrogen-fixing bacteroids are retained within the apoplast in modified infection threads and 2) symbiosomes, where rhizobia are symplastically internalized in the host cell cytoplasm within membrane-bound symbiosomes. Using ...
Pesticide residues contributing to the contamination of soil may influence microbial population of the soil and in turn fertility of soil. The present paper reports the effect of pesticides applied to soybean i.e. phorate, carbofuran,... more
Pesticide residues contributing to the contamination of soil may influence microbial population of the soil and in turn fertility of soil. The present paper reports the effect of pesticides applied to soybean i.e. phorate, carbofuran, carbosulfan, thiomethoxam, imidacloprid, chlorpyriphos and monocrotophos on soil microflora. The viable count of rhizobia and phosphate solubilizing bacteria from rhizospheric soil of soybean ranged between 10(7)-10(8) cfu/g soil which was comparable to the count of bacteria from untreated (control) soil. No significant change in the total viable count of any kind of bacteria due to application of pesticides has been found showing their ability to degrade these pesticides.
