Biology subjects

Radouane, N.

Publications and source records attributed to Radouane, N..

3 recordsLinked to original sources

bioRxiv2026

Compartment-Specific Assembly and Functional Potential of the Bacteriome of Citrullus colocynthis in a Semi-Arid Ecosystem

Plants inhabitng in arid and semi-arid ecosystems, such as Citrullus colocynthis (L.) Schrad., are adapted to drought, heat, salinity, and nutrient limitation. Their associated microbial communities may further support plant persistence under these harsh conditions. Here, we characterized the bacterial communities associated with leaf endosphere, rhizosphere and roots of C. colocynthis growing in a semi-arid region of Moroccan using 16S rRNA gene amplicon sequencing, culture-dependent isolation, and genome-informed functional profiling of selected isolates. The results revealed a structured microbiome, with rhizosphere harboring the highest bacterial diversity, roots representing an intermediate selective habitat, and the leaf endosphere containing a more restricted assemblage. Communities were dominated by members of the phyla Pseudomonadota, Actinomycetota, Bacillota, and Bacteroidota. Several families associated to plant colonization, nutrient mobilization, and stress tolerance, including Pseudomonadaceae, Microbacteriaceae, Rhizobiaceae, Devosiaceae, and Xanthomonadaceae, showed compartment-specific enrichment. Although soil physicochemical properties influenced bacterial community structure, they explained only part of the variation observed, suggesting that bacteriome assembly is shaped by both environmental conditions and host filtering processes. Culture-bdependant analyses recovered diverse endophytic genera, mainly Achromobacter, Pseudomonas, and Glutamicibacter, most of which were also detected in the amplicon sequencing dataset. Genome-based profiling identified traits related to stress response, osmoprotection, nutrient-related metabolism, colonization, and plant-microbe interactions. Together, these findings highlight C. colocynthis as a reservoir for functionally relevant bacterial diversity with ecological and biotechnological potential in semi-arid environments. ImportanceUnderstanding how plants survive in arid and semi-arid ecosystems is increasingly important in the context of climate change and land degradation. This study demonstrates that Citrullus colocynthis hosts a structured and functionally diverse bacteriome across the leaf endosphere, rhizosphere, and root compartments. By combining amplicon sequencing, cultivation, and genome-informed functional analyses, we identified bacterial taxa and traits associated with stress tolerance, nutrient acquisition, and plant colonization. The recovery of cultivable endophytes with adaptive genomic features highlights the potential of desert plant-associated microbiota as a source of beneficial microorganisms for sustainable agriculture and biotechnological applications in water-limited environments.

microbiology↗

bioRxiv2026

Rational Design of an Arid Plant-Derived Endophytic Consortium Improves Crop Performance under Controlled Conditions

Endophytic bacteria from arid medicinal plants represent a promising source of stress-adapted, plant growth-promoting (PGP) microorganisms. Here, we investigated the cultivable endophytic microbiota of Peganum harmala using both nutrient-rich and diluted media to maximize taxonomic recovery. Isolates were dominated by Bacillota and Gammaproteobacteria, with higher diversity in roots than in shoots. Venn analysis revealed a shared core fraction between compartments, forming the basis for consortium assembly. Nine representative strains belonging to Phyllobacterium, Bacillus, Brevibacillus, Burkholderia, Ralstonia, and Amycolatopsis were selected for functional screening. Pairwise antagonism assays showed high compatibility among Bacillus-related strains, whereas certain taxa exhibited inhibitory interactions, guiding rational consortium design. Functional characterization demonstrated complementary PGP traits, including nitrogen-related activity, phosphate, potassium, and silicate solubilization, siderophore and indole-3-acetic acid production, and ammonia production. No single isolate performed optimally across all traits, supporting a consortium-based strategy. A synthetic bacterial consortium (C2), reconstructed from the core endophytic microbiota using compatibility-guided selection, was evaluated in two crop systems. In vitro flax germination assays showed accelerated radicle emergence and improved vigor index, particularly with C2. Under greenhouse conditions, C2 significantly enhanced flax shoot and root biomass, root architecture, leaf area expansion, and photosystem II performance in sterile soil. In faba bean under natural soil, C2 increased leaf number (p = 0.02) relative to the control. These results indicate that consortia derived from core endophytes of arid medicinal plants can promote plant growth across diverse crops and soil contexts, although effects remain context-dependent and require rigorous field validation. IMPORTANCEEndophytic bacteria can serve as sustainable bioinoculants to enhance crop performance under stress conditions. This study demonstrates that the core microbiota of the arid medicinal plant Peganum harmala can be rationally assembled into a functionally complementary consortium that improves germination, nutrient acquisition, and whole-plant physiological performance in flax and faba bean. By combining compatibility-guided assembly with functional screening, we show that consortium-based strategies may outperform single-strain inoculants. These findings provide insight into the development of scalable, plant growth-promoting microbial consortia and highlight the importance of testing microbial inoculants under multiple environmental contexts to ensure consistent benefits.

microbiology↗

bioRxiv2026

Deterministic abiotic filtering and halophilic core microbiomes shape bacterial communities in costal salt flats (Sabkha) of southern Morocco

Coastal salt flats, locally known as Sabkhas, are hypersaline, alkaline desert ecosystems that impose extreme abiotic stress on microbial and plant life. Despite their ecological significance, plant-associated microbiomes in these habitats remain poorly characterized. In this study, we investigated the bacterial communities of native halophytes across three sabkha sites in southern Morocco using an integrated culture-independent and culture-dependent framework. Soil physicochemical analyses revealed strong gradients in salinity and ionic composition, along with consistently alkaline pH across sites. These conditions strongly structured bacterial assemblage: alpha diversity declined progressively from bulk soil to rhizosphere soil, root and shoot; and beta diversity showed clear compartmental separation driven by environmental factors. Canonical Correspondence Analysis identified electrical conductivity (EC), Na2O, K2O and carbonate fractions as the main abiotic drivers. Across plant species, bacterial communities converged toward a stable halophilic core microbiome dominated by Halomonas, Kushneria and Marinococcus, with 66% of ASVs shared across compartments. Host identity played a secondary role, as environmental filtering overshadawed host-specific associations. Culture-dependent isolation recovered 19 halophilic and halotolerant bacterial strains, mainly, Halomonas, Idiomarina, Marinobacter, Psychrobacter, Planomicrobium and Bac illus, tolerating up to 25% NaCl. The strong concordance between cultured isolates and metabarcoding profile confirms that dominant halophilic lineages are both ecologically robust and readily culturable. Together, these findings demonstrate that sabkha plant microbiomes are primarily shalped by deterministic abiotic filtering and harbor resilient, stress-adapted bacterial communities. Sabkhas thus represent promising reservoirs of halophilic microbes with potential applications in saline agriculture and improving crop resilience under extreme environmental conditions. ImportanceCoastal salt flats (sabkhas) are among the most extreme terrestrial environments, characterized by high salinity, alkalinity, and limited water availability. As soil salinization expands worldwide, understanding how life persists in such habitats is increasingly important for sustainable agriculture. This study shows that sabkha ecosystems impose strong environmental filtering on plant-associated bacterial communities, leading to highly structured microbiomes across soil, root, and shoot compartments. Despite differences among sites and plant species, bacterial communities converged toward a shared halophilic core microbiome, dominated by salt-adapted genera that are resilient to extreme ionic stress. Importantly, many of these dominant bacteria were readily culturable, highlighting sabkhas as accessible reservoirs of stress-tolerant microbes. Our findings demonstrate that abiotic conditions outweigh plant identity in shaping microbiome assembly under extreme stress and reveal sabkha halophytes as valuable natural models for discovering microbes with potential applications in saline agriculture, soil restoration, and crop resilience in salt-affected environments.

microbiology↗