Aug 2026· Agronomy· Vol 16, pp. 1500· 0 citations· 49 references
TL;DR
This study isolated a biocontrol strain, Bacillus subtilis Z-294, which demonstrated strong inhibition of P. capsici disease through mechanisms associated with changes in the plant microbiome and holds great promise as a multifunctional biocontrol agent for the sustainable management of diseases and the enhancement of plant health.
Abstract
The soil-borne oomycete pathogen Phytophthora capsici poses a serious threat to plant growth and results in substantial economic impact on the pepper industry. Therefore, the isolation of multifunctional biocontrol agents has become a major research priority. In this study, we isolated a biocontrol strain, Bacillus subtilis Z-294, which demonstrated strong inhibition of P. capsici in both plate and greenhouse experiments. This strain Z-294 exhibited broad-spectrum antagonistic activities as well as plant growth-promoting ability. Phylogenetic analysis based on core-genome and average nucleotide identity (ANI) further identified Z-294 as B. subtilis. Importantly, we found that the strain Z-294 alleviates the P. capsici disease through mechanisms associated with changes in the plant microbiome. Plants treated with Z-294 showed higher alpha-diversity. The application of B. subtilis Z-294 showed that the relative abundance of Alphaproteobacteria, Bacilli, Bacteroidia, Agaricomycetes, and Eurotiomycetes increased, while the relative abundance of Gammaproteobacteria and Sordariomycetes declined. Strain Z-294 holds great promise as a multifunctional biocontrol agent for the sustainable management of diseases and the enhancement of plant health, laying a solid foundation for its future agricultural applications.
Southern blight caused by Sclerotium rolfsii is a devastating soil-borne disease of Aconitum carmichaelii, a medicinal plant widely cultivated in China. Biological control using beneficial bacteria offers a sustainable alternative to chemical fungicides. This study investigated the influence of Bacillus subtilis FZ-7 on rhizosphere microbiome assembly and disease suppression in A. carmichaelii under field conditions. Four treatments were established: uninoculated control (C group), single inoculation with B. subtilis (B group), single inoculation with S. rolfsii (S group), and co-inoculation of S. rolfsii and B. subtilis (BS group). Plant biomass, soil physicochemical properties, and rhizosphere bacterial and fungal communities were analyzed using high-throughput sequencing of 16S rRNA and ITS genes, along with co-occurrence network analysis. Results showed that B. subtilis inoculation suppressed this growth suppression. B. subtilis alone enhanced both bacterial and fungal diversity. PCoA and LEfSe analyses revealed distinct microbial community structures among treatments, with biomarkers such as Lactobacillus, Candidatus Nitrosotalea, Rhodanobacter, and Sphingomonas for bacteria, and Trichocladium, Conocybe, Plectosphaerella, and Athelia for fungi. Co-occurrence network analysis indicated that co-inoculation of S. rolfsii and B. subtilis partially restored cooperative microbial associations. Soil organic matter, pH, and cation exchange capacity were the main environmental factors shaping microbial community composition. Shoot fresh weight in BS recovered to 2.98 kg and rhizome fresh weight to 3.72 kg, representing 73.0% and 41.2% increases over the S treatment. Additionally, the disease index was reduced by 55.26 in BS compared with the control group. Nay more, Bacillus, Chujaibacter, and Rhodanobacter taxa were significantly enriched in BS group. In conclusion, B. subtilis FZ-7 effectively mitigates southern blight in A. carmichaelii by modulating rhizosphere microbial assembly, enriching beneficial taxa, and stabilizing microbial co-occurrence networks, highlighting its potential as a biocontrol agent for sustainable medicinal plant production.
Xiaofang Sun, Yong Liu, Peng-Sheng Ye et al.· Plants· 0 citations
Abstract Fusarium wilt of tomato, caused by Fusarium oxysporum f. sp. lycopersici, is a major constraint to global production, causing up to 80% yield loss under favourable conditions. Plant growth-promoting rhizobacteria (PGPR) offer an eco-friendly alternative for disease management through growth promotion and pathogen suppression. This study aimed to isolate and characterise PGPR from tomato rhizosphere soils across different agro-climatic zones of Assam and evaluate their antagonistic potential under in vitro and glasshouse conditions. A total of 216 isolates were obtained, of which six showed strong antifungal activity (64–83% inhibition) in dual culture assays. Glasshouse evaluation revealed significant reduction in disease incidence (64.80–80.73%) over control. Molecular identification classified these isolates into Bacillus, Pseudomonas, Clostridium, Lysinibacillus, and Achromobacter. Biochemical analyses confirmed production of indole acetic acid, ammonia, siderophores, and phosphate-solubilizing compounds. These results demonstrate the potential of indigenous PGPR isolates as promising biocontrol agents for suppressing Fusarium wilt of tomato under greenhouse conditions. However, field validation and experiments including pathogen-free PGPR treatments are required to distinguish direct plant growth promotion from disease suppression before practical application.
L. Giri, Daisy Senapoty, P. Kaman et al.· Archives of Phytopathology a...· 0 citations
Bacterial and fungal diseases cause significant losses in horticultural crops, and biocontrol using beneficial microorganisms offers a sustainable alternative to chemical pesticides. In this study, a novel Pseudomonas strain D3 was isolated from Actinidiae rhizosphere. D3 exhibited strong antibacterial activity in LB medium but showed no activity against fungi or oomycetes. However, when cultured in KIDO medium, it demonstrated potent antifungal activity. Phylogenetic analysis based on 16S rRNA gene showed that D3 was most closely related to Pseudomonas mosselii CIP_105259T, while whole-genome sequencing revealed ANI values below 95% with eight known P. mosselii strains. Digital DNA-DNA hybridization (dDDH) further confirmed its genomic distinctiveness, with the highest dDDH value (58.2%) against the type strain P. mosselii DSM 17497T, well below the 70% species delineation threshold, supporting D3 as a novel Pseudomonas species. Functional validation via targeted gene knockout revealed a dichotomy in the antagonistic mechanisms of D3. Knockout of individual biosynthetic gene clusters (BGCs) only partially reduced antibacterial activity against Pseudomonas syringae pv. actinidiae, indicating that multiple BGCs contribute to this activity in a partially redundant manner. In contrast, disruption of a specific lipopeptide synthase cluster completely abolished antifungal activity against Valsa mali. LC-MS/MS analysis confirmed that this lipopeptide was produced exclusively in KIDO medium, consistent with the observed medium-dependent antifungal activity. Detached leaf and twig assays showed that D3 provides strong preventive biocontrol against both pathogens. Collectively, strain D3 employs a dual biocontrol mechanism, combining antibacterial activity mediated by multiple BGCs with lipopeptide-dependent antifungal activity, positioning it as a promising agent for sustainable disease management in horticultural crops.
Ming-Ming Yang, Guang-Zhe Li, Yun-Cong Wang et al.· Pesticide Biochemistry and P...· 0 citations
Pronounced cultivar × treatment interactions confirmed that PGPR efficacy is modulated by host genetic background, with resistant varieties carrying pyramided Xa resistance genes showing additive responses to biological treatment.
S. Naqvi, Ateeq ur Rehman, Ummad ud Din Umar· World Journal of Microbiolog...· 0 citations
Pepper (Capsicum annuum L.) is a major vegetable cultivated for seasoning in Korea. Peppers are typically grown as seedlings and transplanted into fields. Infection with Rhizoctonia solani immediately before transplantation can cause significant damage and loss during cultivation. The effectiveness of chemical fungicides is becoming increasingly limited owing to pesticide resistance, emphasizing the need for sustainable agricultural practices. This study aimed to identify a novel biocontrol agent by investigating tidal flat microorganisms capable of controlling damping-off disease in pepper caused by Rhizoctonia solani. Furthermore, we studied the inhibitory effects of different Bacillus species on the mycelial growth of R. solani AG-4 (KACC 40141) for the biological control of damping-off disease. Of the 116 bacterial strains from the tidal flats tested, five (including Bacillus sp. JB005) showed strong inhibitory activity in dual-culture assays against R. solani AG-4. These strains also demonstrated siderophore production, suggesting their potential to suppress damping-off in pepper. We screened useful agricultural traits (e.g., biofilm formation, IAA production, and phosphate solubilizing activity); the most promising strains were used for greenhouse experiments. The results indicated that Bacillus sp. JB005 strongly inhibited damping-off in pepper, suggesting that Bacillus sp. JB005 could serve as a biocontrol agent against R. solani infections.
Chae Yeon Hwang, M. Chandrasekaran, S. Chun· Microbiology Research· 0 citations
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