Response of seedling rhizosphere microbial community to low-temperature and high-moisture stress and enhancement of stress resistance by the synthetic microbial community

Abstract

Combined low-temperature and high-moisture stress is a common abiotic stress during the maize sowing period in Northeast China, severely restricting the normal development of maize seeds and seedlings. Rhizosphere microorganisms play a crucial role in assisting plants to resist adversity. To investigate the response of the rhizosphere microbial community to the stress and its function, a simulation experiment was conducted with two treatments: low-temperature and high-moisture stress (ST) and normal conditions (CT). Under each treatment, maize seeds were sown in three different substrates: quartz sand (SA), sterilized soil (SS), and natural soil (NS). The results showed that compared to SA and SS treatments, the NS treatment was most effective in mitigating the inhibitory effects of stress on seed germination rate, and seedling biomass. Analysis of 16S rRNA gene amplicon sequencing revealed that the relative abundance of taxa with plant growth-promoting potential, such as Pseudomonas, Paenibacillus, and Bacillus, increased significantly in suffering stress treatments. Representative strains from these taxa were further isolated, and their plant growth-promoting traits, including indole-3-acetic acid production, siderophore production, and nitrogen-fixing were verified. Based on common ASVs analysis and strain isolation results, a synthetic microbial community (SynCom) composed of six strains was constructed. Under stress conditions, this SynCom significantly promoted seedling growth. This study elucidated the response patterns of the maize seedling rhizosphere microbial community to stress, clarified the functions of key beneficial microbial taxa, and provided a theoretical basis and microbial resources for developing microbiome-based cultivation technologies to enhance maize stress resistance.