Bacillus altitudinis AD13-4 Enhances Saline-Alkali Stress Tolerance of Alfalfa and Affects Composition of Rhizosphere Soil Microbial Community

• Published in: International journal of molecular sciences 2024-06, Vol.25 (11), p.5785
• Main Authors: Khoso, Muneer Ahmed, Wang, Mingyu, Zhou, Zhenzhen, Huang, Yongxue, Li, Shenglin, Zhang, Yiming, Qian, Guangtao, Ko, Song Nam, Pang, Qiuying, Liu, Changli, Li, Lixin
• Format: Article
• Language: English
• Subjects: Abiotic stress; Adaptation; Airlines; Alkalies; alkaline–sodic stress; Antioxidants; Bacillus - genetics; Bacillus - physiology; Biomass; Cell differentiation; Cellular signal transduction; Chlorophyll; Corn; Food security; Homeostasis; Isoflavones; Medicago sativa - growth & development; Medicago sativa - microbiology; Metabolism; Microbiota; Microbiota (Symbiotic organisms); Microorganisms; Oxidative stress; PGPR; Plant growth; Plant metabolites; plant–PGPR interaction; Polyamines; Proteins; Rhizosphere; rhizosphere microbiota; Rice; RNA; Salt Tolerance; secondary metabolism; Signal transduction; Soil - chemistry; Soil Microbiology; Stress, Physiological
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms25115785

Saline and alkaline stresses limit plant growth and reduce crop yield. Soil salinization and alkalization seriously threaten the sustainable development of agriculture and the virtuous cycle of ecology. Biofertilizers made from plant growth-promoting rhizobacteria (PGPR) not only enhance plant growth and stress tolerance, but also are environmentally friendly and cost-effective. There have been many studies on the mechanisms underlying PGPRs enhancing plant salt resistance. However, there is limited knowledge about the interaction between PGPR and plants under alkaline-sodic stress. To clarify the mechanisms underlying PGPR's improvement of plants' tolerance to alkaline-sodic stress, we screened PGPR from the rhizosphere microorganisms of local plants growing in alkaline-sodic land and selected an efficient strain, AD13-4, as the research object. Our results indicate that the strain AD13-4 can produce various growth-promoting substances to regulate plant endogenous hormone levels, cell division and differentiation, photosynthesis, antioxidant capacity, etc. Transcriptome analysis revealed that the strain AD13-4 significantly affected metabolism and secondary metabolism, signal transduction, photosynthesis, redox processes, and plant-pathogen interactions. Under alkaline-sodic conditions, inoculation of the strain AD13-4 significantly improved plant biomass and the contents of metabolites (e.g., soluble proteins and sugars) as well as secondary metabolites (e.g., phenols, flavonoids, and terpenoids). The 16S rRNA gene sequencing results indicated that the strain AD13-4 significantly affected the abundance and composition of the rhizospheric microbiota and improved soil activities and physiochemical properties. Our study provides theoretical support for the optimization of saline-alkali-tolerant PGPR and valuable information for elucidating the mechanism of plant alkaline-sodic tolerance.