Understanding how soil microbial communities are impacted by climate change is critical given their diverse ecosystem services, particularly in semiarid regions of West Africa. Here, we performed Illumina‐MiSeq amplicon sequencing analysis of the gyrB and 18S rRNA genes to investigate the diversity, structure, and distribution of bacterial and arbuscular mycorrhizal (AM) fungal communities and their main drivers along a rainfall and temperature gradient in the Senegalese peanut basin (SPB). The study revealed that the bacterial communities were dominated by the phyla Actinomycetota, Pseudomonadota, Bacillota, and Bacteroidota, whereas the fungal community was dominated by the classes Glomeromycetes, Paraglomeromycetes, and Archaeosporomycetes. Thirteen glomeromycotan genera were found within nine families ordered according to relative abundance: Glomeraceae, Paraglomeraceae, Claroideoglomeraceae, Gigasporaceae, Entrophosporaceae, Archaeosporaceae, Diversisporaceae, Acaulosporaceae, and Ambisporaceae. These taxa varied in abundance among sites. Overall, the data provided evidence that the microbial communities were influenced by the soil physicochemical properties, rainfall regimes and temperature variability. Both bacterial and AM fungal richness and Shannon-entropy diversity indexes decreased at the low- and high-rainfall sites compared to the moderate-rainfall sites, with bacteria being more responsive to rainfall and temperature dynamics than AM fungi. The bacterial co-occurrence network was also more complex at the moderate-rainfall sites, with the shorter path lengths among interacting species, suggesting higher community efficiency. The soil microbiome was shaped by a broad range of edapho-climatic factors, particularly pH, ammonium content, carbon content, soil texture, rainfall, and temperature. This study represents the first comprehensive survey of SPB soil microbiomes, filling a significant knowledge gap on projected climate-induced changes in microbial communities.

Symbiotic nitrogen fixation (SNF) is a complex process regulated by numerous genes extensively studied in legumes that undergo intracellular infection, such as Lotus japonicus, Medicago truncatula, and Glycine max. However, the molecular and genetic mechanisms of SNF in legumes that rely on the intercellular infection pathway, such as peanut (Arachis hypogaea L.), remain poorly understood. In a previous study, we identified two chromosome segment substitution lines (CSSLs), 12CS_051 and 12CS_044, each contains a wild segment on homeologous regions of chromosomes A02 and B02 respectively, that are severely impaired in nitrogen fixation. In this study, we have compared the transcriptomes of those lines with that of their recurrent parent, Fleur11, in roots inoculated with the effective Bradyrhizobium vignae strain ISRA400 to identify candidate genes associated with the reduced nitrogen fixation observed in these CSSLs. A comparative analysis of the transcriptome profiles of the CSSLs and Fleur11 revealed significant changes in the expression of genes involved in plant immune signaling and key symbiotic genes, such as NIN, EFD, FEN1 or SNF-related transporters. These results align with the phenotypic differences observed during the symbiotic process in the CSSLs. When focusing on each QTL region, we found that only the orthologs of the symbiotic gene FEN1, which is responsible for the failure in the enlargement of infected cells in L. japonicus, exhibited a lack of expression in the two CSSLs compared to Fleur11. FEN1 encodes a homocitrate synthase that is essential for the nitrogenase activity. We hypothesize that changes in the expression of FEN1 could affect the nitrogenase activity, potentially leading to the unfair SNF observed in these lines. In this study, we analyzed the expression profiles of two ineffective nitrogen-fixing chromosome segment substitution lines and identified FEN1 as a suitable candidate gene involved in peanut symbiosis. This research provides valuable insights into understanding and improving SNF in peanut.

Soybean (Glycine max) is a protein-rich legume crop that plays an important role in achieving food security. The aim of this study was to isolate soybean-nodulating rhizobia from Côte d’Ivoire soils and evaluate their potential as efficient strains in order to develop local bioinoculants. For this objective, 38 composite soil samples were collected from Côte d’Ivoire’s five major climatic zones. These soils were used as substrate to trap the nodulating rhizobia using the promiscuous soybean variety R2-231. A total of 110 bacterial strains were isolated and subsequently identified. The analysis of ITS (rDNA16S-23S), glnII and recA sequences revealed a relatively low genetic diversity of these native rhizobia. Moreover, the ITS phylogeny showed that these were scattered into two Bradyrhizobium clades dominated by the B. elkanii supergroup, with ca. 75% of all isolates. Concatenated glnII-recA sequence phylogeny confirmed that the isolates belong in the majority to ‘B. brasilense’, together with B. vignae and some putative genospecies of Bradyrhizobium that needs further elucidation. The core gene phylogeny was found to be incongruent with nodC and nifH phylogenies, probably due to lateral gene transfer influence on the symbiotic genes. The diversity and composition of the Bradyrhizobium species varied significantly among different sampling sites, and the key explanatory variables identified were carbon (C), magnesium (Mg), nitrogen (N), pH, and annual precipitation. Based on both shoot biomass and leaf relative chlorophyll content, three isolates consistently showed a higher symbiotic effectiveness than the exotic inoculant strain Bradyrhizobium IRAT-FA3, demonstrating their potential to serve as indigenous elite strains as bioinoculants.

The poultry sector has grown significantly in the recent years. Certainly, the rise in the global population, particularly in developing nations, has prompted the expansion of the poultry farm sector to fulfill the growing demand for food. The activity produces organic waste and the management of which can pose problems in the farms. Poultry farming requires energy for the production processes. It is in this context this study aims to examine the energy potential of poultry waste depending where it came from (factory farm or domestic farm). The methanogenic potential of these wastes was determined using the Biochemical Methane Potential (BMP) test on poultry droppings from factory farms or domestic farms and other wastes as controls, such as cow and horse dung. The tests showed that the poultry droppings from factory farms had higher gas content and methane (CH4) than the controls. The link between biogas production and the chemical composition of the poultry droppings, was also demonstrated. These findings suggested that poultry droppings from factory farms can be used to produce biogas and/or energy. The latter can be reused for the needs of the farm itself.

Rhizosphere microorganisms, particularly arbuscular mycorrhizal fungi (AMF), play a vital role in enhancing sustainable maize production. However, uncertainty persist regarding the influence of climate variables and soil properties on mycorrhizal colonization (MC) of maize and the abundance of AM fungal spores in the field. This study aimed to explore the environmental factors such as site climate variables, soil physicochemical properties and topography and vegetation variable, affecting the natural MC of maize and the density of AMF spores. The study hypothesizes that natural maize mycorrhizal colonization and AMF spore density vary significantly across different sites and agroecological zones. It further posits that climatic and edaphic variables predominantly explain the observed variation in mycorrhizal parameters. To assess the impact of these factors, a field study was conducted in 32 sites across three territories in the province of South Kivu, namely Kabare, Walungu, and Uvira. Rhizospheric soil and maize roots were collected from different sites. Maize MC varied significantly among sites, with Kabare and Walungu showing high colonization rates (52.1% and 44.7%, respectively) compared to Uvira (26.40%). Meanwhile, spore density was significantly higher in Uvira (1331.7 spores g-1 soil) than in Kabare (518.9 spores g-1 soil) and Walungu (468.58 spores g-1 soil). Correlation analysis indicated that maize MC was influenced by site climate and soil properties. The PLS-SEM model demonstrated that 76.5% (R2) of the total variance in maize root MC was explained by climatic variables and soil chemical properties. Compared to soil chemical properties, climate characteristics had a more pronounced impact on maize MC. Maize MC was inversely correlated with temperature, C and available P content, while being directly and positively correlated with altitude, rainfall, and base saturation rate. Furthermore, 68.5% (R2) of the spore density variability of AMF was explained by climatic variables and soil physical properties. Spore density was inversely correlated with sand and clay content, field capacity, rainfall, and altitude, while being positively correlated with temperature. The results of this study indicate that climatic conditions exert a more pronounced influence on the mycorrhizal colonization of maize and the density of AMF spores than soil characteristics.

Peanut is a key component of Senegal’s predominantly cereal-based farming systems, but its production is challenged by low soil fertility. Rhizobial inoculation is a promising strategy to improve crop yield and reduce the use of chemical nitrogen fertilizers. The aim of this study was to isolate the most specific and effective bradyrhizobial strain for peanut, and to determine the degree of variability in the response of peanut cultivars to inoculation. The seeds of five cultivars: 55-437, Fleur 11, Sunu Gaal, Amoul Morom and Essamaay were inoculated individually with ten bradyrhizobial strains (LMG9283 and USDA3187, which are the reference strains; ISRA400, ISRA453, ISRA454, ISRA519, ISRA534 and ISRA538, isolated from Fleur 11 in Senegal, and ORS3640 and ORS3644, isolated from herbaceous species that are commonly found in Senegalese farmers’ fields). The plants were grown under greenhouse conditions in a mixture of sandy soil and vermiculite (1/1, v/v). The results obtained in terms of nodule formation, plant growth and yield parameters showed a positive effect of bradyrhizobial inoculation. However, these data indicated that the response of peanut to inoculation was cultivar dependent, with the traditional cultivars 55-437 and Fleur 11 showing the greatest increase in plant growth and yield parameters. Our results also highlighted the need for cultivar-specific selection of Bradyrhizobium to improve inoculation success in peanut, with the indigenous isolates being specifically more effective than the reference strains. According to this study, it would be beneficial to promote the use of native isolates that perform well with the peanut cultivars studied. Key words: Peanut (Arachis hypogaea), inoculation, indigenous and exotic Bradyrhizobium strains, nodulation, growth, yield parameters.

A new Bradyrhizobium vignae strain called ISRA400 was isolated from groundnut (Arachis hypogaea L.) root nodules obtained by trapping the bacteria from soil samples collected in the Senegalese groundnut basin. In this study, we present the draft genome sequence of this strain ISRA400, which spans approximatively 7.9 Mbp and exhibits a G+C content of 63.4%. The genome analysis revealed the presence of 48 tRNA genes and one rRNA operon (16S, 23S, and 5S). The nodulation test revealed that this strain ISRA400 significantly improves the nodulation parameters and chlorophyll content of the Arachis hypogaea variety Fleur11. These findings suggest the potential of Bradyrhizobium vignae strain ISRA400 as an effective symbiotic partner for improving the growth and productivity of groundnut crop.

The aim of this investigation was to evaluate the symbiotic performance of a collection of ten plant growth-promoting rhizobacteria (PGPR) strains on the growth and yield attributes of five groundnut varieties.The screening was conducted in the greenhouse using seeds of the varieties Essamay, Amoul Morom, 55-437, Fleur 11 and Sunu Gaal grown in 1.5 kg pots with Sangalkam soils.Leaf chlorophyll content, plant height, number of branches, biomass production, number and mass of pods were the parameters evaluated in response to groundnut inoculation.Overall, the results highlighted the effectiveness of inoculation with certain PGPRs on the growth and yield parameters.However, the effects of the inoculants were highly dependent on the variety used and the parameter studied.In particular, the strains RF8, SI12, SR6, SI16, SI27 and SS10 were the most efficient in improving the plant growth and yield attributes of the varieties Essamay, Amoul Morom and Sunu Gaal.In contrast, Fleur 11 and 55-437 were less responsive in terms of yield attributes, demonstrating that the response to groundnut inoculation is variety dependent.In addition, a significant increase in the estimated leaf chlorophyll content was only observed in Fleur 11 and Sunu Gaal, which was not expected and could be attributed to a lower N 2 fixation capacity of the indigenous rhizobia.Nevertheless, the increases in growth and yield parameters obtained in this study can be considered as a promising data for the use of bacterial biofertilisers in groundnut cultivation.

Climatic variability and the scarcity of rainfall have intensified the process of soil salinization, leading to land degradation and loss of rice yield. A field experiment was conducted to study the effect of cultural mode and organo-mineral fertilizers on rice performance and soil chemical properties. A split plot design with four replications and two factors that were cultural mode (flat and ridge) and fertilizers (mineral, organic, organo-mineral, and control) was carried out. Observations on growth, yield parameters, and yield of rice and soil chemical properties (pH and EC) were recorded. The cultural mode influenced significantly rice performance. Height (76.26 cm), tillers (89.93 m-2), panicles (71.66 m-2), biomass (3252.25 kg ha-1), 1000 kernel weight (12.85 g) and yield (1123.14 kg ha-1) were significantly higher in ridge than flat. However, infertility (44.74%), sterility (58.04%), and survival (91.86%) were higher in flat than ridge mode. However, sowing of rice on ridges with mineral and organo-mineral amendments improved yield parameters increasing the yield of rice more than in flat mode. Soil chemical properties were significantly influenced by cultural modes and fertilizers. Ridge mode increased the soil pH and reduced the salinity more than in flat. Organic and organo-mineral fertilizers affected significantly the soil's chemical parameters by improving the pH and reducing the salinity. Ridge mode combined with organo-mineral amendment improved rice performance and soil chemical properties. Cultural modes and fertilizer types were critical elements to improve soil pH, salinity, and yield.

Peanuts (Arachis hypogaea L.) are an allotetraploid grain legume mainly cultivated by poor farmers in Africa, in degraded soil and with low input systems. Further understanding nodulation genetic mechanisms could be a relevant option to facilitate the improvement of yield and lift up soil without synthetic fertilizers. We used a subset of 83 chromosome segment substitution lines (CSSLs) derived from the cross between a wild synthetic tetraploid AiAd (Arachis ipaensis × Arachis duranensis)4× and the cultivated variety Fleur11, and evaluated them for traits related to BNF under shade-house conditions. Three treatments were tested: without nitrogen; with nitrogen; and without nitrogen, but with added0 Bradyrhizobium vignae strain ISRA400. The leaf chlorophyll content and total biomass were used as surrogate traits for BNF. We found significant variations for both traits specially linked to BNF, and four QTLs (quantitative trait loci) were consistently mapped. At all QTLs, the wild alleles decreased the value of the trait, indicating a negative effect on BNF. A detailed characterization of the lines carrying those QTLs in controlled conditions showed that the QTLs affected the nitrogen fixation efficiency, nodule colonization, and development. Our results provide new insights into peanut nodulation mechanisms and could be used to target BNF traits in peanut breeding programs.

Afin d’améliorer le potentiel productif des terres rizicoles tout en préservant la biodiversité ligneuse, l’association judicieuse des cultures et des arbres est une alternative de choix. Cela devra toutefois passer auparavant par la détermination de l’impact des substrats des arbres d’intérêt (litière, terreau) sur la culture du riz. L’objectif de cette étude a été d’étudier la décomposition de la litière de Parkia biglobosa et de déterminer l’effet de l’amendement de cette litière sur la croissance et le rendement du riz. Un dispositif en bloc randomisé avec neufs traitements répétés trois fois, constitué de quatre doses de litière de feuille (F1[500g/m2 ], F2[1000g/m2 ], F3[1500g/m2 ], F4[2000g/m2 ]), de gousse (G1 [300 g/m2 ], G2 [600 g/m2 ], G3 [900 g/m2 ], G4 [1200 g/m2 ]) et un témoin (T [0 g/m2]) a été mis en place. Il ressort de ces résultats que La coque des gousses a eu une décomposition beaucoup plus rapide suivies des tiges et des folioles. Les taux de germination de riz les plus élevés ont été observés avec les petites doses de litière [G1 (80%) et F2 (72%)]. Sur le plan morphologique (tallage, feuille et hauteur), les doses les plus élevées de gousses (G4 et G3) et de feuilles (F3 et F4) ont été globalement plus performantes. Les rendements en grain les plus élevés ont été observés avec les traitements G4 (2,94 t/ha), G3 (1,44 t/ha), F4 (1,42 t/ha) et F3 (1,40 t/ha) et ce, comparé au témoin Pr= 0,000294. Ainsi, l’influence de la litière de Parkia biglobosa observée, laisse présager une association bénéfique pour la culture du riz.

Aims: Trees outside of protected areas play an important role in providing ecosystem services. They participate in the development of the mat by creating favorable conditions for the development of grasses. The influence of trees on the development and distribution of grasses is not well known. It is in this sense that this study was conducted to determine the effect of Parkia biglobosa cover on the composition, diversity, structure and spatial distribution of herbaceous vegetation. Place and Duration of Study: The study was carried out in the commune of Nyassia in Lower Casamance on a site identified as a Parkia biglobosa park in the Katouré valley in August 2021. Methodology: Floristic surveys were conducted under (R, R/2, R and 2R) and outside the control tree canopy. Results: It was found that the number of species under the tree canopy ranged from 13 to 16 species and was greater than that observed outside the canopy (6 species). Species such as Bracharia deflexa, Cyperus esculentus, Echinochloa colona, Indigofera heudelotii and Pentodon pentandrus were the most frequently encountered in the surveys under the tree canopy (0R, R/2 and R). In contrast, Andropogon gayanus and Bulbostylis capillaris were the most abundant species in the noncanopy surveys. The canopy cover of P. biglobosa, which ranged from 70±17.6 (2R) to 83±19.4 (R/2), was higher than in the uncovered level (54±15.4). Diversity analysis revealed that the canopy surveys 0R (0.80±0.06), R/2 (0.81±0.04) and R (0.77±0.06) were the most diverse. Conclusion: The presence of Parkia biglobosa influenced the presence of herbaceous species and improved habitat conditions.

Context of the Study: The use of organic amendments could help increase the resilience of lowland rice in Lower Casamance to salinity. The aim of this study was to test the effect of different organic amendments (biochar and compost) on the salinity tolerance of lowland rice in Basse Casamance. Objective: The aim was to test the effect of different organic amendments on the salinity tolerance of rice in the lowlands of the villages of Selecky and Essyl in Lower Casamance. Methodology: A split-plot design was adopted with two factors: the type of organic amendment with 4 treatments (biochar, compost, compost + biochar and the control) and salinity with two treatments (salted and unsalted zones). These treatments were repeated 3 times in two consecutive years, 2020 and 2021, at the Selecky and Essyl sites. Physico-chemical characteristics as well as rice growth and production parameters were studied. Results: In the saline zone, soil amendments significantly increased the number of tillers and the height of rice plants compared with controls (p<0.05). Average rice yield and plant biomass were significantly higher in the amended plots at Selecky in both experimental years (p<0.05). At Essyl, on the other hand, height, number of tillers, rice yield and plant biomass were lower in the 2nd year of experimentation. Organic amendments had a significant effect (p<0.05) on rice production and yield parameters in the salt zone.

Aims: The aim of this study was to investigate the effects of organo-mineral amendments on rice growth under saline stress conditions. Study Design: A 3x8 factorial block design was adopted, with 3 concentration levels: 0, 1.94 and 3.88 g/l NaCl and 8 different amendments: control, phosphogypsum (Phos), compost (C), biochar (B), Phos+C, Phos+B, B+C and Phos+B+C. This system was repeated 3 times in 3 blocks. Organics amendments were applied at a rate of 5 kg/m² and 0,2 kg/m² for phosphogypsum. Place and Duration of Study: The trial was conducted from April to June 2021 on the farm of the Agroforestry Department of the Assane SECK University of Ziguinchor, located at 12°32 - 88' N, 16°17 - 23' W, in the Ziguinchor region. Methodology: After two months of cultivation under semi-controlled conditions, growth parameters were measured. In fact, the survival rate is obtained by counting the number of plants that have survived, and the height of the plants is determined using a graduated ruler. The number of tillers was obtained by counting the number of branches and the diameter using a caliper at the base of the crown. Root and above-ground biomass were determined by weighing the plants after 72 hours of oven-drying at 70°C. Results: For the amended treatments, plant survival rate was 100% compared with unamended controls, where plant survival decreased with increasing salinity, with rate of 96, 80 and 70% corresponding to 0; 1,94 and 3,88 g/l NaCl respectively. The number of tillers, crown diameter and above-ground and root biomass of the plants were significantly higher (pr < 0,001) for compost amendments alone (C) and those combined with compost: B+C, Phos+C, Phos+B+C, regardless of the salinity level. Conclusion: The combined use of organic and chemical amendments could enable farmers to restore salinity-affected soils and improve rice growth.

Aims: The objective of this study was to determine the effect of soil sampled under E. camaldulensis on peanut development and microbial community. Place and Duration of Study: Soil sampling at the 0-10 cm horizon was conducted at different distances: 1.5 m, 3 m, 4.5 m, 6 m and 30 m from 3 randomly selected E. camaldulensis plants in four sites: Karamba, Nicia, Rokout and Dioncome. Methodology: A two-factor randomized complete block design was set up in a greenhouse experiment and parameters such as chlorophyll content, acetylene reducing activity, mycorrhization rate, number of nodules, mass of dry matter and microbial community structure were studied. Results: No significant difference was noted among the parameters regardless of the sampling distance for the Karamba, Nicia and Dioncome sites (P>0.05). In the case of Rokout site, however, the chlorophyll content measured at 4.5 m was significantly different from the chlorophyll content measured at 1.5 m from the tree. For aboveground dry biomass, no significant difference was noted regardless of sampling distance at Karamba and Rokout sites except for samples collected at 4.5 m (Pa≤0, 045; Pc≤0.029). No significant difference was also noted for root biomass regardless of sampling distance at the Karamba, Rokout, and Dioncome sites (P>0.05). However, at Nicia, the biomass of the control treatment was significantly higher compared to others (P=0.021). Nodulation did not vary according to sampling distance (P>0.05). The amount of nitrogen fixed is higher at 6 m from Eucalyptus compared to other distances at the Karamba and Nicia sites (P<0.02). In contrast, at Boucotte it is higher at 1.5 m from the tree (P<0.03). Mycorrhization intensity was significantly higher at 6 m and 30 m from the tree compared to other distances. Conclusion: Microbial community structure differed between soil collected under and outside of the canopy of E. camaldulensis.

Termites are key soil bioturbators in tropical ecosystems. Apart from mound nests constructed by some advanced lineages, most of the species use their faeces, oral secretions, debris, or soil aggregates to protect themselves from predators and desiccation when they go out to forage. Although this soil 'sheeting' is considered to play a key role in soil functioning, the properties of this termite-made material has been poorly studied. The few available data showed that sheeting properties are highly variable with positive, neutral or negative impacts on soil C and clay content, and consequently on soil aggregate stability. Therefore, the objective of this study was to determine the factors controlling the physical (particle size fractions and structural stability) and chemical (pH, electrical conductivity and carbon content) properties of soil sheeting produced by termite species encompassing all feeding and building categories using a dataset representative of an important diversity of biotopes coming from 21 countries from all continents colonized by termites. We showed that sheeting properties were explained by the properties of their environment, and especially by those of the bulk soil (linear relationships), followed in a lesser extent by the mean annual precipitation and biotope. Classic hypotheses related to termite feeding and building strategies were not hold by our analysis. However, the distinction of termites into fungus-growing and non-fungus growing species was useful when differentiating the impact of termites on soil electrical conductivity, C content, and structural stability. The large variability observed suggests the need to redefine termite functional groups based on their impacts on soil properties using a trait-based approach from morphological, anatomical and/or physiological traits.

Plant growth promoting microbes (PGPMs) play major roles in diverse ecosystems, including atmospheric nitrogen fixation, water uptake, solubilization, and transport of minerals from the soil to the plant. Different PGPMs are proposed as biofertilizers, biostimulants, and/or biocontrol agents to improve plant growth and productivity and thereby to contribute to agricultural sustainability and food security. However, little information exists regarding the use of PGPMs in micropropagation such as the in vitro plant tissue culture. This review presents an overview of the importance of PGPMs and their potential application in plant micropropagation. Our analysis, based on published articles, reveals that the process of in vitro classical tissue culture techniques, under strictly aseptic conditions, deserves to be reviewed to allow vitroplants to benefit from the positive effect of PGPMs. Furthermore, exploiting the potential benefits of PGPMs will lead to lessen the cost production of vitroplants during micropropagation process and will make the technique of plant tissue culture more efficient. The last part of the review will indicate where research is needed in the future.