The microbiota associated to xerophyte is a “black box” that might include microbes involved in plant adaptation to the extreme conditions that characterize their habitat, like water shortage. In this work, we studied the bacterial communities inhabiting the root system of Argania spinosa L. Skeels, a tree of high economic value and ecological relevance in Northern Africa. Illumina 16S rRNA gene sequencing and cultivation techniques were applied to unravel the bacterial microbiota’s structure in environmental niches associated to argan plants (i.e., root endosphere, rhizosphere, root-surrounding soil), not associated to the plant (i.e., bulk soil), and indirectly influenced by the plant being partially composed by its leafy residue and the associated microbes (i.e., residuesphere). Illumina dataset indicated that the root system portions of A. spinosa hosted different bacterial communities according to their degree of association with the plant, enriching for taxa typical of the plant microbiome. Similar alpha- and beta-diversity trends were observed for the total microbiota and its cultivable fraction, which included 371 isolates. In particular, the residuesphere was the niche with the highest bacterial diversity. The Plant Growth Promotion (PGP) potential of 219 isolates was investigated in vitro, assessing several traits related to biofertilization and biocontrol, besides the production of exopolysaccharides. Most of the multivalent isolates showing the higher PGP score were identified in the residuesphere, suggesting it as a habitat that favor their proliferation. We hypothesized that these bacteria can contribute, in partnership with the argan root system, to the litter effect played by this tree in its native arid lands.

与旱生植物有关的微生物群是一个“黑盒子”，其中可能包括与植物适应适应其生境特征的极端条件有关的微生物，例如缺水。在这项工作中，我们研究了细菌群落栖息的根系刺阿干树仁L. Skeels ，在北非具有高经济价值和生态意义的树。应用Illumina 16S rRNA基因测序和培养技术来揭示与摩洛哥坚果植物（即根内圈，根际，根系周围土壤）相关但与植物无关（即散装土壤）的环境生态位中细菌微生物群的结构，以及间接影响是由植物的一部分由其叶状残留物和相关的微生物（即残留球体）组成。Illumina数据集表明棘刺农杆菌的根系部分根据它们与植物的关联程度，可以容纳不同的细菌群落，从而丰富植物微生物组的典型分类群。对于总微生物群及其可培养部分，其中包括371个分离株，观察到相似的α和β多样性趋势。尤其是，残留球是细菌多样性最高的生态位。在体外调查了219个分离株的植物生长促进（PGP）潜力，除了生产胞外多糖外，还评估了与生物肥料和生物防治有关的几个特征。大多数显示较高PGP分数的多价分离株在残留球中被鉴定出，表明它是有利于其增殖的栖息地。我们假设这些细菌可以与坚果根系统共同起作用，