The Queretaro semi-desert in central Mexico is the most southern extension of the Chihuahua desert. This semi-arid zone shelters a vast cactus diversity with many endemic species. Currently, two cacti species from this semi-desert namely, Echinocactus platyacanthus and Neobuxbaumia polylopha are under a threat to their survival. So far, there are no reports on the bacterial communities associated with these plants. In this study, we assessed the structure and diversity of the rhizospheric bacterial communities associated with Echinocactus platyacanthus and Neobuxbaumia polylopha growing in wild and cultivated conditions. Samples of E. platyacanthus were also approached with culture-based methods in search of isolates with plant growth promoting abilities. Metagenomic DNA was extracted from rhizospheric samples and used for Illumina sequencing of the 16S rRNA gene. α-diversity and amplicon sequence variant (ASV) richness were higher in both groups of E. platyacanthus samples. All samples accounted for 14 phyla, and the major 6 were common to all treatments. The dominant phyla in all four sample groups were Actinobacteria and Proteobacteria. Analysis at family and genus levels showed association patterns with the cultivated samples from both species grouping together, while the wild samples of each cactus species were grouping apart. High abundance values of Rubrobacteraceae (15.9–18.4%) were a characteristic feature of wild E. platyacanthus samples. In total, 2,227 ASVs were scored in all 12 rhizospheric samples where E. platyacanthus samples showed higher richness with 1,536 ASVs. Regarding the growing conditions, both groups of cultivated samples were also richer accounting for 743 and 615 ASVs for E. platyacanthus and N. polylopha, respectively. The isolates from E. platyacanthus rhizosphere were mainly assigned to Bacilli and Gammaproteobacteria. In total 35 strains were assayed for PGPR traits (IAA and siderophore production, phosphate solubilization, and fungal growth inhibition). Strains obtained from plants growing in the wild displayed better PGPR characteristics, stressing that naturally occurring wild plants are a source of bacteria with diverse metabolic activities, which can be very important players in the adaptation of cacti to their natural environments.

墨西哥中部的克雷塔罗半沙漠是奇瓦瓦沙漠的最南端延伸。这个半干旱地区拥有丰富的仙人掌多样性和许多特有物种。目前，这片半沙漠中有两种仙人掌，即扁刺金龟子和多叶新黄杨他们的生存受到威胁。到目前为止，还没有与这些植物相关的细菌群落的报道。在这项研究中，我们评估了与扁刺金龟子和多叶新黄杨在野生和栽培条件下生长。样本扁棘桉还采用基于培养的方法来寻找具有植物生长促进能力的分离株。从根际样品中提取宏基因组 DNA，并用于 16S rRNA 基因的 Illumina 测序。两组的 α 多样性和扩增子序列变异 (ASV) 丰富度均较高扁棘桉样品。所有样本共 14 个门，其中主要 6 个门是所有处理所共有的。所有四个样本组中的优势门是放线菌门和变形菌门。科和属水平的分析显示了两种仙人掌物种的栽培样本分组在一起的关联模式，而每个仙人掌物种的野生样本则分开分组。红杆菌科的高丰度值 (15.9–18.4%) 是野生细菌的一个特征扁棘桉样品。总共，在所有 12 个根际样本中对 2,227 个 ASV 进行了评分，其中扁棘桉样本显示出更高的丰富度，有 1,536 个 ASV。就生长条件而言，两组栽培样本也更丰富，分别为 743 和 615 个 ASV。扁棘桉和多毛猪笼草， 分别。分离物来自扁棘桉根际主要分布于杆菌和γ变形菌门。总共对 35 个菌株进行了 PGPR 性状（IAA 和铁载体产生、磷酸盐溶解和真菌生长抑制）分析。从野生植物中获得的菌株表现出更好的 PGPR 特性，强调天然存在的野生植物是具有多种代谢活动的细菌的来源，这在仙人掌适应自然环境的过程中发挥着非常重要的作用。