Effects of the plant growth-promoting rhizobacterium Zobellella sp. DQSA1 on alleviating salt-alkali stress in job's tears seedings and its growth-promoting mechanism

Plant probacteria as a sustainable microbial resource are crucial to plant, which not only promote plant growth but also increase the stress resistance of plants. In this study, whole-genome sequencing of Zobellella sp. DQSA1 was performed, and Zobellella sp. DQSA1 was applied to Job's tears seedings under salt-alkali stress. Whole-genome analysis revealed that Zobellella sp. DQSA1 can produce metabolites such as tryptophan, alpha-linolenic acid and other products through metabolism. In response to the action of Zobellella sp. DQSA1, the contents of jasmonic acid (JA) and indole-3-acetic acid (IAA) in the root system increased by 32.5% and 81.4% respectively, whereas the content of abscisic acid (ABA) decreased by 30.0%, and the contents of other endogenous hormones also significantly differed. Additionally, the physiological and biochemical indices related to growth and salinity demonstrated notable differences. Finally, sequencing analysis revealed that 57 differentially expressed genes (DEGs) were involved in 16 Gene Ontology (GO) pathways. Furthermore, the correlations between the contents of endogenous hormones and 57 DEGs were analyzed, and JA was found to be the most significantly correlated. These results provide a theoretical basis for further exploration of the functions and mechanisms of plant growth-promoting rhizobacteria (PGPR) under salt-alkali stress.