Phenotypic and genetic diversity in Sinorhizobium meliloti and S. medicae from drought and salt affected regions of Morocco

<p>Abstract</p> <p>Background</p> <p><it>Sinorhizobium meliloti </it>and <it>S. medicae </it>are symbiotic nitrogen fixing bacteria in root nodules of forage legume alfalfa (<it>Medicago sativa </it>L.). In Morocco, alfalfa is usually grown in marginal soils of arid and semi-arid regions frequently affected by drought, extremes of temperature and soil pH, soil salinity and heavy metals, which affect biological nitrogen fixing ability of rhizobia and productivity of the host. This study examines phenotypic diversity for tolerance to the above stresses and genotypic diversity at Repetitive Extragenic Pallindromic DNA regions of <it>Sinorhizobium </it>nodulating alfalfa, sampled from marginal soils of arid and semi-arid regions of Morocco.</p> <p>Results</p> <p><it>Rsa</it>I digestion of PCR amplified 16S rDNA of the 157 sampled isolates, assigned 136 isolates as <it>S. meliloti </it>and the rest as <it>S. medicae</it>. Further phenotyping of these alfalfa rhizobia for tolerance to the environmental stresses revealed a large degree of variation: 55.41%, 82.16%, 57.96% and 3.18% of the total isolates were tolerant to NaCl (>513 mM), water stress (-1.5 MPa), high temperature (40°C) and low pH (3.5), respectively. Sixty-seven isolates of <it>S. meliloti </it>and thirteen isolates of <it>S. medicae</it> that were tolerant to salinity were also tolerant to water stress. Most of the isolates of the two species showed tolerance to heavy metals (Cd, Mn and Zn) and antibiotics (chloramphenicol, spectinomycin, streptomycin and tetracycline). The phenotypic clusters observed by the cluster analysis clearly showed adaptations of the <it>S. meliloti </it>and <it>S. medicae </it>strains to the multiple stresses. Genotyping with rep-PCR revealed higher genetic diversity within these phenotypic clusters and classified all the 157 isolates into 148 genotypes. No relationship between genotypic profiles and the phenotypes was observed. The Analysis of Molecular Variance revealed that largest proportion of significant (P < 0.01) genetic variation was distributed within regions (89%) than among regions (11%).</p> <p>Conclusion</p> <p>High degree of phenotypic and genotypic diversity is present in <it>S. meliloti </it>and <it>S. medicae </it>populations from marginal soils affected by salt and drought, in arid and semi-arid regions of Morocco. Some of the tolerant strains have a potential for exploitation in salt and drought affected areas for biological nitrogen fixation in alfalfa.</p

Contribution de la recherche agricole pour une meilleure résilience de l’agriculture marocaine

L’agriculture joue un rôle socio-économique important au Maroc. Elle représente 13 % du Produit National Brut du pays et engage environ 46 % de la population. La stratégie du Plan Maroc Vert 2008-2020 a contribué significativement à l’agriculture marocaine à travers le renforcement des filières agricoles, l’augmentation de la productivité et de l’export.  Le changement climatique qui engendre une pluviométrie insuffisante et des températures élevées réduit la productivité des principales cultures. De plus l’augmentation de la population engendre une demande croissante en produits agricoles. Avec les autres facteurs géopolitiques comme la guerre en Ukraine, qui a impacté disponibilité et prix des céréales et oléagineuses, le pays est contraint de développer une agriculture plus résiliente pour sécuriser ses besoins essentiels en produits agricoles de base comme les céréales, les légumineuses, les viandes, les fruits et légumes.  La recherche agricole joue un rôle clé pour accompagner la stratégie Génération Green (2020-2030) à travers plusieurs programmes visant une agriculture innovatrice, productive et résiliente. Cet article présente d’abord le contexte général de sécurité et souveraineté alimentaire, suivis par les outils et les solutions aux différents défis liés au nexus biodiversité-sol-eau, base de productivité et de résilience. La conservation des ressources génétiques est primordiale pour la sélection de variétés résilientes et productives des différentes cultures. Ainsi le Maroc renforce ses capacités dans ce domaine, avec une nouvelle banque de gènes de l’ICARDA focalisant sur les accessions de céréales et légumineuses. Un centre national des ressources génétique verra le jour en 2024 et inclura toutes les cultures importantes pour l’agriculture marocaines. Récemment, des nouvelles variétés de blé ont été développées affichant des rendements jusqu’à 30% supérieurs à la variété témoin en année de sécheresse. Des variétés de cactus résistantes à la cochenille ont été sélectionnées grâce à une collection de plus de 300 génotypes et sont actuellement en multiplication en vue de leur distribution aux petits agriculteurs. L’agriculture de précisions est une priorité pour une utilisation plus raisonnée des intrants en particulier l’eau et les fertilisants. La mise en œuvre du semis direct pour faire face aux problèmes de sècheresse et de santé du sol a été lancée avec succès depuis 2020 pour couvrir 1 M ha d’ici 2030. Enfin, l’adoption de l’agroforesterie qui contribue à l’amélioration des rendements via un programme de plantation de plusieurs cultures comme celui de 100 000 ha de caroubier.  Toutes ces actions contribueront au développement d’une agriculture résiliente conduisant le Maroc vers sa souveraineté alimentaire

Dynamic composting optimization through C/N ratio variation as a startup parameter

Different organic wastes (waste of tomato leaves and stems, sheep manure, olive mill waste and melon waste) were mixed with different proportions for different C/N ratio to make better use of tomato waste as it constitutes the majority of horticultural waste in the Souss-Massa region (south-western of Morocco). The objective of this study was to evaluate the effect of C/N ratio on the physicochemical parameters during aerobic composting process (temperature, relative humidity, pH, EC...), and the quality of the compost. The effect of each produced compost was also tested by its incorporation at different rates into sandy soil. The four studied C/N ratios (treatments) were: C/N=25; C/N=30; C/N=35 and C/N=40. Results revealed that the treatment C/N=35 has resulted in the highest oxygen consumption and also, the longest thermophilic phase. Treatments C/N=25 and C/N=35 have reached optimal C/N ratios at the end of the process (respectively 11.88 and 14.71), while treatments C/N=30 and C/N=40 stood higher than 15 (respectively 17.93 and 18.84). Fulvic acid evolution remained constant for all treatments, whereas humic acid content has reached highest levels with C/N=25 and C/N=35 treatments. The effect of compost on seed germination test and phytotoxicity test showed that treatment C/N=35 has produced the most mature compost with the lowest phytotoxicity effect. The amendment of compost has reduced the pH, increased the EC, and enriched soil with organic matter as far as the rate of the amendment is increasing (10; 20 and 30Tonnes.ha-1). Compost of treatment C/N=40 has recorded the highest soil total organic matter content poorly decomposed during composting. However compost of treatment C/N=35 has resulted in the lowest soil total organic matter content, this is mainly due to the intense degradation of the compost during the composting process. The quality of the produced compost depends largely on the level of C/N startup ratio and also the quality of its constituents within the mixture

Élever la Résilience Agricole à l'Ère Numérique : Les Avantages et les limites de l'Agriculture Digitale

Le Maroc, pays méditerranéen, fait face à des plusieurs types de défis dont les défis géopolitiques, sanitaire, économique et sociaux dont les défis agricoles croissants dus aux changements climatiques. Cependant, l'adoption de l’agriculture digitale offre des solutions prometteuses pour renforcer l’efficience et l’efficacité en termes d’utilisation des ressources, et par conséquent, la résilience agricole. L'agriculture digitale utilise des technologies telles que les drones et les capteurs pour collecter des données en temps réel sur les conditions des cultures, optimisant ainsi l'utilisation des ressources et minimisant les impacts environnementaux. L'agriculture de précision va encore plus loin en utilisant l'intelligence artificielle pour analyser ces données et prendre des décisions éclairées sur la gestion des cultures, de la détection précoce des maladies à l'optimisation de l'irrigation. Cette approche innovante augmente l'efficacité et l’efficience des agriculteurs, réduit les gaspillages et améliore la durabilité globale des systèmes de production. En adoptant ces technologies, les agriculteurs marocains peuvent accroître leur résilience aux conditions climatiques changeantes et aux autres défis (exemples pour aider le lecteur), tout en contribuant à une agriculture durable et prospère dans la région méditerranéenne

Genotypic characterization of indigenous Sinorhizobium meliloti and Rhizobium sullae by repPCR, RAPD and ARDRA analyses

The rhizobia, Sinorhizobium meliloti and Rhizobium sullae, which fix nitrogen in root nodules of alfalfa (Medicago sativa L.) and sulla (Hedysarum sp.) forage legumes, respectively, were isolated from root nodules and soils from Morocco. We used three PCR-based techniques namely, rep-PCR, RAPD and ARDRA techniques for genotypic characterization of 10 isolates of S. meliloti and R. sullae, in order to identify rapid and reliable techniques for applications in population genetic analysis of these species. The analysis revealed characteristic banding patterns for S. meliloti and R. sullae isolates by all the three techniques, even though the isolates are from a narrow geographic region in Morocco. Furthermore, the results showed that the rep-PCR with REP and ERIC primers was more efficient than RAPD and ARDRA technique for genotyping S. meliloti isolates; and rep-PCR with REP primers and the ARDRA technique with restriction enzyme HinfI, were more efficient than the other rep-PCR and RAPD-PCR techniques for genotyping R. sullae isolates

Co-Inoculation of Mesorhizobium ciceri with Either Bacillus sp. or Enterobacter aerogenes on Chickpea Improves Growth and Productivity in Phosphate-Deficient Soils in Dry Areas of a Mediterranean Region

Biological nitrogen fixation requires a large amount of phosphorus (P). However, most of the soils are P-deficient and the extensive use of P- chemical fertilizers constitute a serious threat to the environment. In this context, two field experiments were carried out to investigate the effect of co-inoculation of Mesorhizobium ciceri with phosphate solubilizing bacteria (PSB), Bacillus sp., and Enterobacter aerogenes, on chickpea as an alternative to chemical nitrogen (N) and phosphorous fertilizers in P-deficient soils in dry areas of Morocco. The results revealed that combined inoculation of chickpea with rhizobia and PSB showed a significant enhancement of chickpea nodulation, biomass production, yields and N, P, and protein content in grains as compared to single inoculation or single application of N or P. A significantly higher increase was obtained by inoculating chickpea with Mesorhizobium sp. MA72 combined with E. aerogenes P1S6. This combination allowed an enhancement of more than 270% in nodulation, 192% in shoot dry weight and 242% in grain yield. The effect of this combination was equivalent to the effect of combined application of N and P fertilizers. Formulation of biofertilizers based on tasted strains could be used for chickpea co-inoculation in P-deficient soils for an eco-friendly sustainable production of chickpea

Elucidation of functional chemical groups responsible of compost phytotoxicity using solid-state 13C NMR spectroscopy under different initial C/N ratios

International audienc

Development and Proof-of-Concept Application of Genome-Enabled Selection for Pea Grain Yield under Severe Terminal Drought

Terminal drought is the main stress limiting pea (Pisum sativum L.) grain yield in Mediterranean environments. This study aimed to investigate genotype &times; environment (GE) interaction patterns, define a genomic selection (GS) model for yield under severe drought based on single nucleotide polymorphism (SNP) markers from genotyping-by-sequencing, and compare GS with phenotypic selection (PS) and marker-assisted selection (MAS). Some 288 lines belonging to three connected RIL populations were evaluated in a managed-stress (MS) environment of Northern Italy, Marchouch (Morocco), and Alger (Algeria). Intra-environment, cross-environment, and cross-population predictive ability were assessed by Ridge Regression best linear unbiased prediction (rrBLUP) and Bayesian Lasso models. GE interaction was particularly large across moderate-stress and severe-stress environments. In proof-of-concept experiments performed in a MS environment, GS models constructed from MS environment and Marchouch data applied to independent material separated top-performing lines from mid- and bottom-performing ones, and produced actual yield gains similar to PS. The latter result would imply somewhat greater GS efficiency when considering same selection costs, in partial agreement with predicted efficiency results. GS, which exploited drought escape and intrinsic drought tolerance, exhibited 18% greater selection efficiency than MAS (albeit with non-significant difference between selections) and moderate to high cross-population predictive ability. GS can be cost-efficient to raise yields under severe drought

La culture de la luzerne dans un climat méditerranéen

Traduction également disponible en arabe (Translation : I. Thami-Alami)booklet is a deliverable of the project REFORMA, Working Package 3La culture de la luzerne dans un climat méditerranée