Getahun Alemayehu, Muleta Diriba, Assefa Fassil, Kiros Solomon
College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia.
Addis Ababa Institute of Technology, Addis Ababa University, Addis Ababa, Ethiopia.
Int J Microbiol. 2020 Oct 29;2020:8897998. doi: 10.1155/2020/8897998. eCollection 2020.
Drought stress (DS) is the most impacting global phenomenon affecting the ecological balance of a particular habitat. The search for potential plant growth-promoting rhizobacteria (PGPR) capable of enhancing plant tolerance to drought stress is needed. Thus, this study was initiated to evaluate the effect of inoculating seedlings with PGPR isolated from rhizosphere soil of Ethiopia to enhance DS tolerance. The strains were selected based on assays associated with tolerance to drought and other beneficial traits such as salinity, acidity, temperature, heavy metal tolerances, biofilm formation, and exopolysaccharide (EPS) production. The strains with the best DS tolerance ability were selected for the greenhouse trials with acacia plants. The results indicate that out of 73 strains, 10 (14%) were completely tolerant to 40% polyethylene glycol. Moreover, 37% of the strains were strong biofilm producers, while 66 (90.41%) were EPS producers with a better production in the medium containing sucrose at 28 ± 2°C and pH 7 ± 0.2. Strains PS-16 and RS-79 showed tolerance to 11% NaCl. All the strains were able to grow in wider ranges of pH (4-10) and temperature (15-45°C) and had high tolerance to heavy metals. The inoculated bacterial strains significantly ( ≤ 0.05) increased root and shoot length and dry biomass of acacia plants. One of the strains identified as strain FB-49 was outstanding in enhancing DS tolerance compared to the single inoculants and comparable to consortia. Stress-tolerant PGPR could be used to enhance acacia DS tolerance after testing other phytobeneficial traits.
干旱胁迫（DS）是影响特定栖息地生态平衡的最具影响力的全球现象。因此，需要寻找能够增强植物对干旱胁迫耐受性的潜在促生根际细菌（PGPR）。因此，本研究旨在评估用从埃塞俄比亚根际土壤中分离的PGPR接种幼苗以增强对干旱胁迫耐受性的效果。这些菌株是根据与干旱耐受性以及其他有益特性（如盐度、酸度、温度、重金属耐受性、生物膜形成和胞外多糖（EPS）产生）相关的测定来选择的。选择具有最佳干旱胁迫耐受能力的菌株用于相思树植物的温室试验。结果表明，在73个菌株中，10个（14%）对40%聚乙二醇完全耐受。此外，37%的菌株是强生物膜生产者，而66个（90.41%）是EPS生产者，在28±2°C和pH 7±0.2的含蔗糖培养基中产量更高。菌株PS-16和RS-79对11% NaCl表现出耐受性。所有菌株都能在较宽的pH范围（4-10）和温度范围（15-45°C）内生长，并且对重金属具有高耐受性。接种的细菌菌株显著（≤0.05）增加了相思树植物的根和茎长度以及干生物量。鉴定为FB-49菌株的其中一个菌株在增强干旱胁迫耐受性方面比单一接种剂更出色，且与混合接种剂相当。在测试其他植物有益特性后，耐胁迫的PGPR可用于增强相思树对干旱胁迫的耐受性。
