Soil microbial communities are closely associated with ecosystem functions. However, unravelling the complex nature of the microbial world and successfully utilizing all positive interactions for multipurpose environmental benefits is still a major challenge. Here, we describe the soil bacterial communities in different niches of healthy and diseased tomatoes under natural conditions. A higher abundance of the pathogen Ralstonia solanacearum and lower bacterial diversity were observed in the disease samples. The healthy tomato rhizosphere harbored more plant-beneficial microbes, including Bacillus and Streptomyces. Also, the co-occurrence network in the healthy rhizosphere samples was more complicated, so as to better adapt to the soil-borne pathogen invasion. Both the beta nearest-taxon-index (βNTI) and normalized stochasticity ratio (NST) analyses demonstrated that healthy rhizosphere communities were less phylogenetically clustered and mainly dominated by dispersal limitation, while homogeneous selection was the major assembly process driving the rhizosphere community of diseased samples. The results obtained with community assembly methods and co-occurrence network analysis revealed that healthy rhizosphere bacterial communities possessed potentially broader environmental stress (soil-borne pathogen stress) adaptability compared with diseased rhizosphere bacterial communities. In conclusion, this study contributed to widening our understanding of the potential mechanisms of soil bacterial community composition and assembly responding to soil-borne pathogen invasion.

Introduction: Excessive chloride ion content in tobacco leaves adversely affects the flammability of flue-cured tobacco, particularly in tobacco-growing regions of northern China, where this issue is more pronounced. Consequently, this poses a challenge for finding economically and environmentally friendly control methods. Vibrio natriegens, as a non-pathogenic, moderately halophilic bacterium, can reduce chloride ion content in soil. Zn²⁺, as a chloride ion channel inhibitor, can effectively reduce the accumulation of chloride ions in plants.Methods: In this study, we established two experimental groups, T1 and T2, where T1 contained V. natriegens as a chloride ion inhibitor and T2 contained Zn²⁺ as a chloride ion inhibitor. We investigated the effects of T1 and T2 on chloride ion content in tobacco, soil environmental factors, and microbial community structure. Various methods were employed to measure soil physicochemical properties, and the impact of different treatments on microbial community structure was elucidated through soil microbial DNA extraction, PCR amplification, PE library construction, Illumina sequencing, and subsequent bioinformatics analysis.Results and discussion: The results indicate that both inhibitors significantly reduced chloride ion levels in tobacco (p < 0.05) and altered the abundance of certain soil microorganisms. Specifically, the chloride ion content in upper leaves decreased from 1.33% to 0.83% under T1 treatment, while the T2 experimental group showed a reduction to 0.99%. Additionally, we evaluated the agronomic traits of tobacco plants and found that the application of chloride ion inhibitors promoted plant growth. Field trials further validated the efficacy of these inhibitors, with treated tobacco leaves exhibiting significantly lower chloride ion content compared to the control group. This study, based on the source of chloride ion uptake by tobacco plants from soil, employed strategies to control soil chloride ion content or reduce plant uptake, thereby effectively managing chloride ion levels in tobacco leaves. This provides an effective strategy for controlling chloride ion content in tobacco leaves, contributing to the high-quality development of tobacco production.

Introduction: Tobacco, as an important economic crop, shows significant growth and yield responses to soil conditions and nutrient supply. In recent years, microbial organic fertilizers (MOF) have garnered significant attention as a novel fertilizer category due to their demonstrated potential for soil quality improvement and plant growth promotion. This study aims to evaluate the effects of MOF on tobacco growth in Hunan Province, with particular focus on its long-term impacts on soil physicochemical properties and rhizosphere microbial communities throughout the tobacco growth cycle. Methods: We evaluated the effects of T1 (Basic fertilizer + Bacillus ), T2 (Basic fertilizer + Pseudomonas ), and T3 (Basic fertilizer + Bacillus and Pseudomonas ) treatments on tobacco quality, soil parameters, and microbial communities. Soil physicochemical properties were measured using standardized analytical methods. Microbial community dynamics under different treatments were analyzed via 16S rRNA sequencing and PICRUSt2 analysis. Results and Discussion: The results indicate that microbial fertilizers can significantly enhance soil fertility and promote tobacco growth by modulating soil microbial communities. Specifically, the T1 organic fertilizer treatment demonstrated the most pronounced effect in reducing microbial abundance, as evidenced by a lower Sobs value of 4, 222 compared to 4, 825 in the control group (p < 0.05). Furthermore, this treatment significantly enhanced the visual quality of tobacco leaves. This study provides a scientific foundation for the application of microbial fertilizers in tobacco cultivation and offers new perspectives for sustainable agricultural development.