Halotolerant rhizobacterial consortia from desert ecosystems alleviate salinity stress in durum wheat through promoting root growth and shaping rhizosphere bacteriome

Abstract Hot desert ecosystems are among the most extreme terrestrial environments, characterized by intense solar radiation, scarce and unpredictable rainfall, high temperatures, and nutrient-poor soils, which together impose strong limitations on biological productivity and ecosystem functioning. Despite these harsh conditions, desert plants thrive through close associations with specialized rhizosphere microbiomes, yet the functional potential of these microbial communities for improving crop stress tolerance remains underexplored. In this study, we investigate the diversity, functional traits, and biotechnological potential of cultivable halotolerant rhizobacteria from three desert ecosystems with contrasting salinity concentrations in southern Morocco: Dunes, Lagoon, and Grara, a hyper-arid, low-salinity desert ecosystem dominated by drought-adapted vegetation. We isolated 31 bacterial isolates from the rhizospheres of native desert plants that exhibited high tolerance to salinity (up to 100 g NaCl L⁻¹) and drought (-0.30 MPa). Bacterial isolates originating from the highly saline Lagoon ecosystem displayed superior salt tolerance compared with those from less saline environments, highlighting ecosystem-driven microbial adaptation. Nine bacterial consortia with contrasting salt-tolerance capacities were developed and evaluated for their ability to mitigate salinity stress in durum wheat under greenhouse conditions. Inoculation with a consortium composed of highly salt-tolerant isolates significantly enhanced shoot biomass (158%), chlorophyll content (182%), and morphological root system traits (16–78%) compared to uninoculated control. Correlation analyses revealed strong associations between root architectural traits and aboveground growth parameters, suggesting that salt-tolerant bacterial consortium enhances plant performance by promoting functional root development and improving resource acquisition under saline conditions. In addition to these direct effects, significant positive correlation ( p < 0.01) between Bacillus genus, the main bacterial group composing the best-performing consortium, and above-belowground growth parameters clearly indicate that the halotolerant consortia are actively mitigating wheat salt stress. Overall, these findings identify desert rhizosphere bacteria as a reservoir of stress-adaptive traits and demonstrate their potential for microbiome-based strategies to enhance crop resilience in saline agroecosystems.