Endophytic Bacillus subtilis ED24 from Ziziphus lotus (L.) Desf. roots enhances wheat performance and shapes rhizosphere microbiota

Ziziphus lotus (L.) Desf. is a resilient shrub native to Morocco’s arid and semi-arid regions. This study aimed to isolate and characterize plant growth-promoting bacteria (PGPB) from the root endosphere of Z. lotus, and to evaluate the most effective strain in planta, assessing its impact on plant germination, growth, and modification of the soil microbiota associated to wheat under greenhouse conditions. Our results showed that among the isolated endophytes, Bacillus subtilis ED24 demonstrated strong plant growth-promoting properties, including solubilization of insoluble phosphorus and zinc, nitrogen fixation, and siderophores production. Findings from the pot experiment demonstrated that B. subtilis ED24 significantly improved germination (96% vs. 83% in control), shoot height (52.76 cm vs. 44.98 cm), leaf area (46.2 cm² vs. 30.82 cm²), and shoot biomass (4.28 g vs. 3.45 g). Inoculation also enhanced shoot potassium content (106.6 mg/pot vs. 63.92 mg/pot), grain yield and quality along with a slight increase in grain protein content (19.50% vs. 18.39%) and grain crude fiber content (2.53% vs. 2.48%). Furthermore, inoculation with B. subtilis ED24 enriched beneficial rhizospheric bacteria (e.g., Cicerobacter, Streptomyces, Ferrovibrio, Rhizobium) and reduced pathogenic fungi, such as Fusarium. These findings highlight the potential of B. subtilis ED24 to promote wheat growth and beneficially shape the wheat-associated microbial community.