لخّصلي

This study provides a detailed characterization of the rhizospheric and endophytic microbiomes associated with three native desert plants--Vachellia gerrardi, Haloxylon salicornicum, and Ziziphus spina-christi--across three contrasting arid regions (Tabuk, Hail, and Arar) within the King Salman Royal Reserve.Harnessing stress-resilient bacterial and fungal taxa identified in this study could contribute to the development of microbe-based strategies for sustainable agriculture, ecological restoration, and land reclamation in arid and semi-arid regions, aligning with national efforts to enhance environmental sustainability and food security.Fungal taxa such as Trichoderma, Chaetomium, and arbuscular mycorrhizal groups further highlight the potential of desert-derived microbes as biological tools for enhancing plant resilience, improving soil fertility, and supporting ecosystem functioning in degraded drylands.

This study provides a detailed characterization of the rhizospheric and endophytic microbiomes associated with three native desert plants—Vachellia gerrardi, Haloxylon salicornicum, and Ziziphus spina-christi—across three contrasting arid regions (Tabuk, Hail, and Arar) within the King Salman Royal Reserve. High-throughput amplicon sequencing of 16S rRNA and ITS markers revealed taxonomically rich and functionally diverse microbial communities dominated by Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Ascomycota, and Basidiomycota. Alpha- and beta-diversity analyses consistently showed that geographic location and associated environmental gradients exert a stronger influence on community structure than host plant identity, with Tabuk supporting the highest microbial diversity and Arar harboring more specialized, stress-tolerant taxa such as Rubrobacter and Truepera.

The identification of a core microbiome shared across regions and plant species, including key drought-tolerant, nutrient-cycling, and plant-growth-promoting genera (e.g., Streptomyces, Bacillus, Pseudomonas, Rhizobium, Sphingomonas, and Nitrospira), underscores the ecological importance of these microbial consortia for plant survival under extreme aridity, heat, and nutrient limitation. Fungal taxa such as Trichoderma, Chaetomium, and arbuscular mycorrhizal groups further highlight the potential of desert-derived microbes as biological tools for enhancing plant resilience, improving soil fertility, and supporting ecosystem functioning in degraded drylands.

Despite its strengths, the study is constrained by its reliance on DNA-based community profiling, single-season sampling, the use of published rather than in situ soil physicochemical data, and a moderate sample size. Future work should therefore integrate multi-season sampling, direct measurement of soil properties, and multi-omics approaches (metagenomics, metatranscriptomics, and metabolomics), coupled with culture-dependent isolation and inoculation trials, to link taxonomic profiles with ecological functions and plant performance.

Overall, our findings lay a foundational framework for understanding how environmental gradients shape desert plant microbiomes in northern Saudi Arabia and highlight the substantial biotechnological potential of these microbial communities. Harnessing stress-resilient bacterial and fungal taxa identified in this study could contribute to the development of microbe-based strategies for sustainable agriculture, ecological restoration, and land reclamation in arid and semi-arid regions, aligning with national efforts to enhance environmental sustainability and food security.