Hnini Mohamed, Aurag Jamal
Microbiology and Molecular Biology Team, Center of Plant and Microbial Biotechnology, Biodiversity and Environment, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, Rabat, 10000, Morocco.
Environ Microbiome. 2024 Sep 27;19(1):73. doi: 10.1186/s40793-024-00611-3.
Soil bacteria often form close associations with their host plants, particularly within the root compartment, playing a significant role in plant growth and stress resilience. Vachellia tortilis subsp. raddiana, (V. tortilis subsp. raddiana)a leguminous tree, naturally thrives in the harsh, arid climate of the Guelmim region in southern Morocco. This study aims to explore the diversity and potential plant growth-promoting (PGP) activities of bacteria associated with this tree.
A total of 152 bacterial isolates were obtained from the rhizosphere of V. tortilis subsp. raddiana. Rep-PCR fingerprinting revealed 25 distinct genomic groups, leading to the selection of 84 representative strains for further molecular identification via 16 S rRNA gene sequencing. Seventeen genera were identified, with Bacillus and Pseudomonas being predominant. Bacillus strains demonstrated significant tolerance to water stress (up to 30% PEG), while Pseudomonas strains showed high salinity tolerance (up to 14% NaCl). In vitro studies indicated variability in PGP activities among the strains, including mineral solubilization, biological nitrogen fixation, ACC deaminase activity, and production of auxin, siderophores, ammonia, lytic enzymes, and HCN. Three elite strains were selected for greenhouse inoculation trials with V. tortilis subsp. raddiana. Strain LMR725 notably enhanced various plant growth parameters compared to uninoculated control plants.
The findings underscore the potential of Bacillus and Pseudomonas strains as biofertilizers, with strain LMR725 showing particular promise in enhancing the growth of V. tortilis subsp. raddiana. This strain emerges as a strong candidate for biofertilizer formulation aimed at improving plant growth and resilience in arid environments.
土壤细菌通常与其宿主植物形成紧密联系，尤其是在根际区域，对植物生长和抗逆性起着重要作用。阿拉伯胶树（Vachellia tortilis subsp. raddiana）是一种豆科树木，自然生长于摩洛哥南部盖勒敏地区恶劣的干旱气候中。本研究旨在探索与该树相关细菌的多样性及其潜在的促进植物生长（PGP）活性。
从阿拉伯胶树的根际共获得152株细菌分离物。重复PCR指纹图谱显示有25个不同的基因组群，从而挑选出84株代表性菌株，通过16S rRNA基因测序进行进一步的分子鉴定。鉴定出17个属，其中芽孢杆菌属和假单胞菌属占主导。芽孢杆菌菌株对水分胁迫表现出显著耐受性（高达30% PEG），而假单胞菌菌株表现出高耐盐性（高达14% NaCl）。体外研究表明，这些菌株在PGP活性方面存在差异，包括矿物溶解、生物固氮、ACC脱氨酶活性以及生长素、铁载体、氨、裂解酶和HCN的产生。挑选出三株优良菌株用于对阿拉伯胶树进行温室接种试验。与未接种的对照植物相比，菌株LMR725显著提高了各种植物生长参数。
研究结果强调了芽孢杆菌属和假单胞菌属菌株作为生物肥料的潜力，菌株LMR725在促进阿拉伯胶树生长方面表现出特别的前景。该菌株成为旨在改善干旱环境中植物生长和抗逆性的生物肥料配方的有力候选者。
