Interactions Between Bacillus atrophaeus 100 MTN1 and Fusarium oxysporum f. sp. lycopersici Reprogram the Transcriptomic and Metabolomic Profile to Combat Tomato (cv. Kalyan) Wilt

Transcriptomic responses of Fusarium oxysporum f. sp. radicis-lycopersici to secreted antimicrobial compounds of Pseudomonas chlororaphis ToZa7

Tripartite interactions shape the biocontrol potential of lactic acid bacteria against Ralstonia solanacearum and Fusarium oxysporum f. sp. cubense race 1

ABSTRACT This study investigated the antagonistic potential of two lactic acid bacteria (LAB) strains, A15 and A55, against the major banana pathogens Fusarium oxysporum f. sp. cubense race 1 (Foc R1), the causal agent of Fusarium wilt, and Ralstonia solanacearum race 2 (Rs), responsible for Moko disease. In vitro assays revealed significant inhibition of Foc R1 and Rs by both LAB strains, and greenhouse experiments showed that their application reduced the severity and delayed the onset of Fusarium wilt symptoms in Gros Michel banana plants (p < 0.05). However, LAB treatments did not mitigate Moko disease; instead, disease severity increased over time in Rs-infected plants, underscoring that in vitro antagonism does not necessarily translate into effective in planta biocontrol. The results further suggest that LAB-mediated suppression of Foc R1 might be influenced by host factors, such as an induction in plant defences, highlighting the complexity of tripartite interactions in biological control. Although LAB effects were limited to disease suppression rather than plant growth promotion, their integration into broader pest management programmes may enhance sustainability and reduce reliance on chemical controls. Future research should focus on elucidating the biochemical mechanisms underlying LAB activity and optimising application strategies under field conditions.

Isolation and Identification of Fusarium oxysporum Causing Cowpea Fusarium Wilt in Hainan and In Vitro Screening of Antagonistic Bacteria

Cowpea (Vigna unguiculata subsp. sesquipedalis, also known as yardlong bean) is an important winter horticultural crop in Hainan, and Fusarium wilt seriously threatens its yield and quality. To clarify the pathogen and screen antagonistic bacteria, surveys were conducted in 14 fields across Hainan’s major cowpea-growing areas. The causal agent was isolated, tested for pathogenicity, and identified using morphological and multigene molecular methods. Meanwhile, rhizosphere and endophytic bacteria from healthy plants were screened by dual culture, and candidate strains were phylogenetically analyzed using whole-genome sequencing (285 orthologous single-copy genes). Fusarium wilt occurred in all 14 fields (mean incidence 15.35%, range 3.20–76.40%). Of 44 fungal isolates, six were highly pathogenic and identified as Fusarium oxysporum. Twenty-two bacterial strains showed stable antagonism against F. oxysporum, with inhibition rates ranging from 42.62% to 68.47%. Phylogenetic analysis based on whole-genome sequences identified 15 Bacillus strains to the species level (12 B. velezensis, 2 B. subtilis, 1 B. tropicus), while the remaining seven strains belonged to Lysinibacillus (1), Pantoea (1), Klebsiella (1), Serratia (2), and Pseudomonas (2). Draft genome sequences of all 22 strains were obtained. This study provides a collection of biocontrol bacterial resources and genomic information for managing cowpea Fusarium wilt.

Transcriptome and Metabolome Dissection of Multilayered Pydiflumetofen Resistance Mechanisms in Fusarium graminearum

Wheat Fusarium head blight (FHB) is a globally prevalent and destructive fungal disease predominantly caused by Fusarium graminearum. Pydiflumetofen, a novel succinate dehydrogenase inhibitor (SDHI) fungicide, exhibits strong inhibitory activity against F. graminearum; however, the molecular regulatory mechanisms underlying the field-developed resistance in this pathogen remain poorly defined. In the present study, a field-evolved resistant isolate W24-039 and a sensitive isolate W24-016 were subjected to multi-omics analysis. The sequencing results identified compound mutations C89S/A93V in SdhC2, and A21T/S30F in SdhD of the resistant strain, which confer stable fungicide resistance without any detectable fitness costs. Physiological tests revealed that these target mutations sustain the homeostasis of succinate dehydrogenase (SDH) activity and intracellular ATP production. Following pydiflumetofen treatment, the sensitive isolate displayed remarkable declines in SDH activity, intracellular ATP content and deoxynivalenol (DON) biosynthesis, accompanied by markedly elevated cell membrane permeability. Transcriptomic sequencing uncovered 2221 differentially expressed genes (DEGs) in the sensitive strain under fungicide stress, and 2566 DEGs in the resistant isolate under the same conditions. The genes associated with detoxification and drug efflux, including cytochrome P450, glutathione S-transferase (GST), ABC and MFS transporters, were significantly upregulated in the resistant isolate. Metabolomic analysis indicated that differential metabolites were mainly enriched in the tricarboxylic acid (TCA) cycle, amino acid metabolism and membrane lipid biosynthesis pathways. The resistant strain maintained intact TCA cycle operation and accumulated high levels of pivotal metabolites such as phosphatidylcholine, unsaturated fatty acids and reduced glutathione. Integrated multi-omics analysis verified that the ABC transporter and glutathione metabolism pathways serve as core regulatory modules governing fungicide resistance. Collectively, F. graminearum develops resistance via the synergistic effects of SDH compound mutations, enhanced detoxification and efflux, and global metabolic remodeling, demonstrating that target-site mutation alone is not the sole driver of resistance, which is instead controlled by an intricate regulatory network involving multiple coordinated pathways. This study systematically characterizes the resistance regulatory network of F. graminearum against pydiflumetofen, and provides theoretical guidance for the rational application and sustainable field resistance management of this fungicide.

Klebsiella sp. IR6, an endophytic rhizobacteria with potential as a plant growth-promoting agent for Jalapeño pepper (Capsicum annum L.) production.

IR6 exhibited the most notable agronomic performance, increasing seedling leaf area, fruit production, and fruit size under field conditions and demonstrating antagonistic activity against Fusarium oxysporum, confirming its potential as a biocontrol agent and PGPR.

Comparative Insights into Bacterial Endophytome and Antifungal Metabolites in Fusarium Wilt-Resistant and -Susceptible Banana Cultivars Unveil the Resistance Toward Fusarium oxysporum f. sp. cubense

India contributes 26% of global banana production, yet cultivation is severely threatened by Fusarium wilt (Fusarium oxysporum f. sp. cubense, Foc), necessitating sustainable, eco-friendly management strategies. This study evaluated the biocontrol potential of endophytic bacteria isolated from Foc-resistant and -susceptible banana cultivars. Isolates from the pseudostem, corm, and root of the resistant cultivar showed significantly greater inhibitory activity than those from the susceptible cultivar, underscoring the role of host genotype in shaping functionally competent endophytic communities. Among all isolates, Bacillus sp. from the corm of cv. Rose (AB) showed the highest mycelial inhibition of Foc (70.37–76.54%) in vitro. GC-MS-based metabolite profiling revealed a chemically diverse array of secondary metabolites, fatty acid esters, steroids, terpenoids, siloxanes, and nitrogenous compounds. Corm-associated endophytes exhibited membrane-disruptive and cytotoxic activity, while root-associated endophytes contributed protective, defense-modulatory effects. Halomonas sp. RoRo2 and B. subtilis RoC1 showed the highest inhibition in both agar-well and in planta assays, with unsaturated fatty acids and organic acid derivatives implicated as key antifungal effectors acting through multiple biochemical pathways. These findings identify metabolically versatile endophytes as promising candidates for developing efficient, environmentally compatible bioinoculants as sustainable alternatives to chemical control of Fusarium wilt in banana.