[Objective] To screen and identify the plant growth-promoting bacterial strain with saline-alkali tolerance and evaluate its functions. [Methods] The rhizosphere soil of wheat was collected from different saline-alkali regions, and the highly efficient saline-alkali-tolerant bacterial strain was isolated by enrichment under saline-alkali condition and dilution coating. The antifungal spectrum and plant growth-promoting effects of the isolate were evaluated in vitro, and the nitrogenase activity was measured by an ELISA kit. The strain was identified based on the morphological, physiological, biochemical characteristics and phylogenetic analysis. The effect of the strain on wheat growth under salt stress was investigated by a pot experiment. [Results] A highly abundant bacterium with saline-alkali tolerance was enriched from rhizosphere soil and designated as TaRb44, which could grow normally under 3% NaCl and pH 10.0. Strain TaRb44 showed strong antagonism against soil-borne pathogenic fungi such as Fusarium pseudograminearum causing wheat crown rot, Fusarium oxysporum f. sp. niveum causing watermelon Fusarium wilt, and Fusarium oxysporum f. sp. cubense causing banana wilt, as well as Botrytis cinerea causing gray mold of postharvest tomatoes. Further tests showed that strain TaRb44 produced a variety of plant growth-promoting substances such as siderophores, amylase, and cellulase, and it had nitrogen fixation activity with the nitrogenase level of 65.50 U/L. Finally, the strain TaRb44 was identified as Paenibacillus polymyxa, which significantly promoted the growth of wheat seedlings and increased the root biomass under both salt stress and non-salt stress conditions. [Conclusion] In this study, P. polymyxa TaRb44 was obtained with much excellent properties such as disease prevention, plant growth promotion, and saline-alkali tolerance. It serves as an elite strain for developing new microbial fertilizer and soil amendments in the future.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |