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, 10000, Rabat, Morocco.
Arch Microbiol. 2022 Dec 28;205(1):45. doi: 10.1007/s00203-022-03358-y.
Nodular endophytes of drought-tolerant legumes are understudied. For this reason, we have isolated and studied non-symbiotic endophytic bacteria from nodules of Vachellia tortilis subsp. raddiana, a leguminous tree adapted to the harsh arid climate of Southern Morocco. Rep-PCR analysis followed by 16S rDNA sequencing revealed two main genera, Pseudomonas and Bacillus. Isolates responded variably to salt and water stresses, and mostly produced exopolysaccharides. Differences concerned also plant growth-promoting activities: phosphate, potassium, and zinc solubilization; biological nitrogen fixation; auxin, siderophore, ammonia, and HCN production; and ACC deaminase activity. Some strains exhibited antagonistic activities against phytopathogenic fungi (Fusarium oxysporum and Botrytis cinerea) and showed at least two enzymatic activities (cellulase, protease, chitinase). Four selected strains inoculated to vachellia plants under controlled conditions have shown significant positive impacts on plant growth parameters. These strains are promising bio-inoculants for vachellia plants to be used in reforestation programs in arid areas increasingly threatened by desertification.
耐旱豆科植物的结节内生菌研究较少。基于此，我们从适应摩洛哥南部恶劣干旱气候的豆科植物 Vachellia tortilis subsp. raddiana 的根瘤中分离并研究了非共生内生细菌。重复序列 PCR 分析结合 16S rDNA 测序揭示了两个主要属，假单胞菌属和芽孢杆菌属。分离株对盐和水胁迫的反应不同，且大多产生胞外多糖。差异还涉及植物促生长活性：磷酸盐、钾和锌的溶解；生物固氮；生长素、铁载体、氨和 HCN 的产生；以及 ACC 脱氨酶活性。一些菌株对植物病原菌（尖孢镰刀菌和灰葡萄孢）具有拮抗活性，并表现出至少两种酶活性（纤维素酶、蛋白酶、几丁质酶）。在受控条件下将 4 株选定的菌株接种到金合欢植物中，对植物生长参数有显著的积极影响。这些菌株有望成为金合欢植物的生物接种剂，用于在日益受到荒漠化威胁的干旱地区进行重新造林计划。
