Pseudomonas protegens SN15-2, a typical non-spore-forming rhizosphere bacterium, has excellent biocontrol capabilities; thus, it is necessary to explore the stress resistance of SN15-2. The choline–glycine betaine pathway is considered as an important mechanism by which bacteria adapt to stressful environments. In this work, we demonstrated that the expression of the betA and betB genes, which are involved in the choline–glycine betaine pathway in SN15-2, was highly increased by 12-fold and 26-fold, respectively, by hyperosmotic stress and choline treatment. The accumulation of betaine in SN15-2 (5.54 g/L) was significantly higher than that in the mutants Δ betA (3.44 g/L) and Δ betB (2.68 g/L) under hyperosmotic stress and choline treatment. Moreover, choline enhanced the growth of SN15-2 greatly, but it did not enhance the growth of Δ betB under hyperosmotic stress. Choline combined with hyperosmotic adaptation significantly increased the lethal stress resistance of SN15-2 while the resistance of Δ betA and Δ betB was significantly decreased. This research illuminated a strategy underlying the adaptation to osmotic stress in P. protegens and provided an effective method to improve the stress resistance of this species, thus provided a theoretical basis for the practical application of P. protegens SN15-2.

中文翻译：

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胆碱-甜菜碱途径有助于假单胞菌 SN15-2 的高渗应激和随后的致死应激抵抗

Pseudomonas protegens SN15-2 是典型的非产孢根际细菌，具有优良的生防能力；因此，有必要探索SN15-2的抗应力性能。胆碱-甘氨酸甜菜碱途径被认为是细菌适应压力环境的重要机制。在这项工作中，我们证明了参与 SN15-2 胆碱-甘氨酸甜菜碱途径的 betA 和 betB 基因的表达分别通过高渗应激和胆碱高度增加了 12 倍和 26 倍。治疗。在高渗胁迫和胆碱处理下，SN15-2中甜菜碱的积累（5.54 g/L）显着高于突变体Δ betA（3.44 g/L）和Δ betB（2.68 g/L）。此外，胆碱极大地促进了 SN15-2 的生长，但在高渗胁迫下并没有促进 Δ betB 的生长。胆碱结合高渗适应显着增加了SN15-2的致死胁迫抗性，而Δ betA和Δ betB的抗性显着降低。该研究阐明了P. protegens适应渗透胁迫的策略，为提高该物种的抗逆性提供了有效方法，从而为P. protegens SN15-2的实际应用提供了理论依据。