Abstract:Background The development and utilization of beneficial plant growth-promoting rhizobacteria (PGPR) resources in the arid regions in northwest China represents a key research focus for sustainable agricultural development. It holds significant importance in the research and development of green microbial fertilizers, the enhancement of crop yields, and the maintenance of soil ecological health.Objective To screen multifunctional beneficial rhizosphere strains from special arid habitats, analyze their genomes and growth-promoting characteristics, and lay a crucial foundation for clarifying the growth-promoting and stress-resistant mechanisms of rhizosphere microorganisms in soybeans in the arid regions of Xinjiang.Methods Strains with excellent nitrogen fixation, phosphate solubilization and potassium dissolution, and other multifunctional characteristics were screened using specific functional media, followed by preliminary physiological and biochemical analyses, as well as studies on their growth-promoting characteristics. Furthermore, these strains were further analyzed by whole-genome sequencing using the Illumina NovaSeq X Plus next-generation sequencing platform.Results In this study, a strain of Acinetobacter sp. A11 (CCTCC M20242725) with multiple plant growth-promoting functions and superior performance was isolated from the rhizosphere of nodular soybeans in the arid habitat of Altay, Xinjiang. The physiological and biochemical results showed that this strain was a Gram-negative bacterium, capable of tolerating 1.5% NaCl and growing within the pH range of 4.0-9.0. The whole-genome sequencing showed that the total genomic length of the strain was 4 512 900 bp under an accession number JBPPST000000000 in NCBI, with a G+C content of 39.44%. Through annotation analysis, a total of 98 genes related to multifunctional growth promotion were identified, among which 50 genes were involved in nitrogen metabolism, including glu, glt, gln, nas and amt. There were 29 genes associated with phosphorus metabolism, involving gdh, pqq, phn, pst, pho and ugp, while 19 genes were related to potassium-solubilizing capacity, primarily including kdp, kef, kup and ktr. In addition, gene clusters (vibB, fhu and fts) related to iron acquisition were also identified, suggesting that the A11 strain may also possess the potential to synthesize siderophores. Furthermore, the multifunctional growth-promoting assay demonstrated that the A11 strain exhibited notable performance across key indices. Specifically, its nitrogenase concentration reached (296.22±4.37) ng/L. Meanwhile, the dissolved organic phosphorus index was measured at 1.70±0.05, and the lecithin conversion amount stood at (3.96±0.05) mg/L. The dissolved inorganic phosphorus index was 1.80±0.08, and the conversion amount of calcium phosphate was as high as (32.96±0.45) mg/L. The potassium-solubilizing index was 2.17±0.03, and the conversion amount of potassium feldspar powder reached (5.91±0.53) mg/L. The seed germination promotion test indicated notable enhancements in germination-related indicators when the seeds were inoculated with strain A11, compared to the non-inoculated control group. Specifically, this inoculation led to a 40.47% increase in seed germination rate and a more substantial 98.13% improvement in plumule length.Conclusion In this study, the Acinetobacter sp. A11 isolated from the rhizosphere of soybeans in the special arid habitat of Xinjiang exhibited superior growth-promoting properties. Further in-depth exploration and analysis of its whole-genome functional genes will provide important reference value for further application of this strain and research on its growth-promoting mechanism.
