Botrytis cinerea causing tomato gray mold is a major cause of economic loss in tomato production. It is urgent and necessary to seek an effective and environmentally friendly control strategy to control tomato grey mold disease. In this study, Bacillus velezensis FX-6 isolated from the rhizosphere of plants displayed significant inhibitory ability against B. cinerea and could promote tomato plant growth. FX-6 could effectively inhibit the growth of Botrytis cinerea mycelium in vitro and in vivo, and the inhibitory rate in vitro could reach 78.63%. According to morphological observations and phylogenetic trees based on sequences of the 16S rDNA and gyrA (DNA gyrase subunit A) genes, the strain FX-6 was identified as Bacillus velezensis. In addition, B. velezensis FX-6 showed antagonistic activity against seven phytopathogens, this indicated that FX-6 had broad-spectrum biocontrol activity. We also found that FX-6 fermentation broth had the strongest antagonistic activity against B. cinerea when the culture time was 72 hours, and the inhibition rate was 76.27%. The growth promotion test revealed that strain FX-6 significantly promoted tomato seed germination and seedling growth. Further deeply study on growth-promoting mechanism indicated that the FX-6 produced IAA and siderophore, and had ACC deaminase activity. The trait of significant biological control activity and growth promoting effect on tomato imply that B. velezensis FX-6 has the potential to be used as a biocontrol agent for tomato gray mold management.

Fusarium root rot caused by the Fusarium species complex significantly affects the yield and quality of Angelica sinensis, a valuable medicinal herb. Traditional management primarily relies on chemical fungicides, which have led to pathogen resistance, environmental hazards, and concerns regarding public health and the active components in A. sinensis. This study explores the efficacy of a novel plant-derived biopesticide Shi Chuang Zhi Feng Ning (T1; SCZFN), alongside Bacillus subtilis wettable powder (T2) and a chemical fungicide (T3), in controlling root rot and understanding their impacts on the rhizosphere microbial community and root metabolome. Results of the field experiment demonstrated that treatments T1 and T3 achieved control efficiencies of 73.17% and 75.45%, respectively, significantly outperforming T2 (39.99%) and the control. High-throughput sequencing revealed that all treatments altered the diversity and structure of microbial communities, with T1 and T2 reducing the abundance of taxa linked to root rot, such as Muribaculaceae spp., Humicola spp., Fusarium spp., and Mycochlamys spp. Treatment T1 notably enhanced beneficial bacterial taxa, including Acidobacteria spp., Nitrospira spp., and Pedosphaeraceae spp., involved in carbon cycling and plant growth promotion. Metabolomic analysis identified 39, 105, and 45 differentially expressed metabolites (DEMs) across the treatments, demonstrating T1’s potential to modulate the root metabolome effectively. Further, a correlation analysis demonstrated a stronger correlation between distinct microorganisms with significant influence and DEMs of T1 treatment compared to other treatments. These findings underscore biopesticide SCZFN’s role in enhancing plant health and disease suppression in A. sinensis, providing insights into its biocontrol mechanisms and supporting the development of sustainable disease management strategies in its cultivation.

Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (FON), is a predominant and devastating soil-borne disease that results in significant yield losses in watermelon cultivation. In this study, a strain MM isolated from the herbage rhizosphere soil, exhibited an inhibition rate of 65.46% against FON, leading to mycelial collapse, atrophy, and deformation. In pot experiments, strain MM effectively controlled Fusarium wilt of watermelon, showing a control efficacy of 74.07%. Through morphological observation and 16S rDNA gene sequencing, strain MM was identified as Serratia plymuthica. Additionally, S. plymuthica MM demonstrated antagonistic activity against eight plant pathogens, indicating that MM had broad-spectrum antifungal activity. The strain also exhibited the ability to synthesize siderophores and indole acetic acid (IAA), both of which are growth-promoting compounds. Moreover, strain MM secreted various extracellular enzymes, including protease, chitinase, β-glucanase, and cellulase. This ability allowed S. plymuthica MM to readily colonize watermelon roots and promote seedling growth. Inoculation with S. plymuthica MM increased the activity of PAL, POD, PPO, and CAT enzymes associated with watermelon defense. Furthermore, qRT-PCR analysis revealed up-regulation of LOX, POD, PAL, ClPR3, and C4H genes, which are related to plant disease resistance. The results indicated that S. plymuthica MM enhances watermelon plants’ resistance to FON by activating the JA, SA, and shikimic acid phenylpropanoid–lignin synthesis pathways. Gas chromatography–mass spectrometry (GC-MS) analysis of S. plymuthica MM culture supernatant identified piperazinedione, pyrrolo[1,2-a]pyrazine-1,4-dione, and octadecenamide as the main antimicrobial substances. Overall, S. plymuthica MM shows promise as a biocontrol agent against Fusarium wilt of watermelon, suggesting its potential for the development of a new biocontrol agent.

Fusarium avenaceum is the predominant fungal pathogen responsible for root rot in Angelica crops and poses a serious threat to their commercial quality and yield in China. This fungus produces enniatin B (ENN B), a toxin that could be a pathogenicity and virulence factor in plant–pathogen interactions. Yet whether ENN B exacerbates host infection and the onset of root rot in Angelica spp. caused by F. avenaceum is surprisingly understudied. Pathogenicity assays revealed that ENN B co-inoculation with F. avenaceum significantly increased the root rot disease index in Angelica sinensis from 83.33% (pathogen alone) to 92.86% (p < 0.05). Toxin degradation experiments showed that the bacteria Paenibacillus polymyxa and Bacillus tequilensis were capable of degrading 60.69% and 70.02% of ENN B, respectively. Response surface optimization (24.5 °C, 22.01 mg/L ENN B, 0.99% inoculum) enhanced degradation by B. tequilensis to 81.94%, a 11.74% improvement. Three ester compounds were identified by LC-HRMS as potential degradation products of ENN B. In planta trials demonstrated that the disease index was 50.01% for the group co-inoculated with ENN B degradation products and F. avenaceum, a 42.85% reduction compared to the group co-inoculated with ENN B and F. avenaceum. This study provides a new microbial strategy for controlling root rot in Angelica crops from a mycotoxin degradation perspective, which can be applied to promote sustainable agricultural production.

Scutellaria baicalensis Georgi is a member of the plant family Lamiaceae and is widely cultivated in China as a medicinal plant (Wang et al. 2021). In August 2022, an investigation of a 10-hectare ...

Potato black scurf, caused by Rhizoctonia solani, is a widespread soil-borne disease in major potato-producing regions that reduces potato yield and tuber marketability. This study evaluated the field growth-promoting effects and disease-control efficacy of Bacillus velezensis HZ33 on the potato cultivars Xindaping and Longshu 7 and assessed its impact on rhizosphere microbial communities. Field trials showed that the application of HZ33 significantly enhanced potato growth and increased the chlorophyll content, yield, and commercial tuber rates. HZ33 also raised key soil nutrient levels. Its control efficacy against potato black scurf exceeded that of the chemical fungicide azoxystrobin. Application of HZ33 reduced the relative abundance of Rhizoctonia associated with black scurf and increased the relative abundance of beneficial fungi and bacteria. The microbial community structure correlated with both soil chemical properties and the disease index for potato black scurf. Overall, B. velezensis HZ33 appears to be a promising biocontrol agent for suppressing potato black scurf while improving potato yield.