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BACKGROUND: Peach brown rot, caused by the pathogen Monilinia fructicola, represents a significant postharvest infectious disease affecting peach fruit. This disease is responsible for a substantial increase in fruit decay rates, leading to significant economic losses, often exceeding 50%. Currently, there is a growing interest in identifying biocontrol agents to mitigate peach brown rot, with a predominant interest in Bacillus species. RESULTS: In this investigation, we isolated 410 isolates of actinomycetes from non‐farmland ecosystem soil samples. Subsequently, 27 isolates exhibiting superior inhibitory capabilities were selected. Among these, strain XDS1‐5 demonstrated the most robust fungistatic effect against brown rot disease, achieving an 80% inhibition rate in vitro and a 66% inhibition rate in vivo. XDS1‐5 was identified as belonging to the Streptomyces virginiae species. Furthermore, a fermentation filtrate of XDS1‐5 exhibited the ability to metabolize 34.21% of the tested carbon sources and 7.37% of the tested nitrogen sources. Particularly noteworthy was its capacity to disrupt the cell membrane structure directly, leading to increased cell membrane permeability and cytoplasmic leakage. Additionally, our investigation indicated that indoline, a metabolite produced by XDS1‐5, played a pivotal role in inhibiting the growth of M. fructicola. CONCLUSION: In summary, our study has identified a biocontrol actinomycete, XDS1‐5, with the potential to effectively inhibit postharvest brown rot disease in peaches. This finding holds great significance for the biological control of peach brown rot, offering promising prospects for mitigating the economic losses associated with this devastating disease. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Peach brown rot, attributed to Monilinia fructicola, presents a significant threat to postharvest peach cultivation, causing losses of up to 80%. With an increasing number of countries, spearheaded by the European Union, imposing bans on chemical agents in fruit production, there is a growing interest in mining highly active antibacterial compounds from biological control strains for postharvest disease management. In this study, we highlight the unique ability of Streptomyces lincolnensis strain JCP1‐7 to inhibit M. fructicola sporulation, despite its limited antimicrobial efficacy. Through GC–MS analysis, eucalyptol was identified as the key compound. Fumigation of diseased fruits with eucalyptol at a concentration of 0.0335 μg cm−3 demonstrated an in vivo inhibition rate against M. fructicola of 93.13%, completely suppressing spore formation. Transcriptome analysis revealed the impact of eucalyptol on multiple pathogenesis‐related pathways, particularly through the inhibition of catalase 2 (Cat2) expression. Experiments with a MfCat2 knockout strain (ΔMfCat2) showed reduced pathogenicity and sensitivity to JCP1‐7 and eucalyptol, suggesting MfCat2 as a potential target of JCP1‐7 and eucalyptol against M. fructicola. Our findings elucidate that eucalyptol produced by S. lincolnensis JCP1‐7 inhibits M. fructicola sporulation by regulating MfCat2, thereby effectively reducing postharvest peach brown rot occurrence. The use of fumigation of eucalyptol offers insights into peach brown rot management on a large scale, thus making a significant contribution to agricultural research. [ABSTRACT FROM AUTHOR]

Background: Pepper blight, caused by Phytophthora capsici, is a destructive soilborne disease, which poses a serious threat to pepper, Capsicum annuum L., production. Chemical fungicides, which mainly are used to control pepper blight, have a negative effect on the environment, rendering biological control as a promising alternative to maintain the balance between ecology and pest management. The purpose of this study was to screen the biocontrol bacteria, reduce the dosage of fungicides and increase the stability of biocontrol bacteria, and to find the mixing ratio of biocontrol bacteria and fungicides giving the best control effect. Results: We isolated actinomycetes strains from the soil surrounding the roots of healthy pepper plants amongst field‐grown plants infected with P. capsici. Of these, Streptomyces albus XJC2‐1 showed a strong inhibition effect on the growth of P. capsici, with an inhibition rate of ≤85%. XJC2‐1 effectively inhibited the formation of sporangium and release of zoospores of P. capsici as well as directly destroyed its hyphae, to achieve the inhibitory effect. Transcriptomic profiling of pepper leaves, postirrigation of plants with the XJC2‐1 fermentation broth, revealed upregulation of genes related to the photosynthesis pathway in pepper. Furthermore, XJC2‐1 treatment improved the net photosynthetic rate and intercellular CO2 concentration, thereby improving the pepper plant's resistance to pathogens. The combination of XJC2‐1 with the fungicide dimethomorph (8 μg mL−1) displayed strong synergism in inhibition of P. capsici infection, with a control efficiency as high as 75.16%, thus providing a basis for its application in the field. Conclusion: Our study demonstrated that S. albus XJC2‐1 inhibited Phytophthora pathogens from infecting pepper plants and enhanced plant host resistance. The combination of XJC2‐1 and dimethomorph displayed a more stable and stronger control effect on pepper blight, showing potential for the future application of XJC2‐1 in the field of biological control. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The wildfire disease on tobacco can seriously hinder plants. Meanwhile, its pathogen, Pseudomonas syringae, can also infect over 200 plants and threat agriculture production. However, the disease usually occurs after summer rains which washes away most copper (Cu)‐based bactericides, allowing the disease to invade. Therefore, we fabricate a new nanogel with high disease control and anti‐erosion ability and study the effects of the reductant on the performance of the copper oxide nanoparticle (CuONP) composite nanogel. Results: Polydopamine (PDA) is a polycation for both in situ reduction of CuONP in alginate nanogels and for adjusting the copper ion (Cu2+) releasing rate in this work. The composite nanogel fabricated by PDA (PDA‐CuONP@ALGNP@CTAC) had a higher Cu2+ releasing rate, damaging the pathogen membrane more efficiently, allowing for better disease control and plant growth promotion when compared to sodium borohydride (SBH)‐fabricated nanogel (SBH‐CuONP@ALGNP@CTAC) or the commercial bactericide, thiodiazole copper. The PDA‐CuONP@ALGNP@CTAC had a high anti‐erosion ability and could remain adhered to the leaf surface even after five rain event simulations. Conclusion: The addition of polycations (like PDA) into CuONP composite nanogel could increase the Cu2+ releasing rate, resulting in improved disease management when compared to SBH‐CuONP@ALGNP@CTAC or thiodiazole copper. The PDA containing gel had an improved anti‐erosion ability and water resistance. This new composite nanogel has a high potential for wildfire disease control, improving agricultural production. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Antibacterial photocatalytic therapy has been employed as a promising strategy to combat antibiotic‐resistant bacteria in the water disinfection field, especially some non‐metal inorganic nanomaterials. However, their antibacterial activities on plant phytopathogens are poorly understood. Here, the photocatalytic antibacterial mechanism of the urea‐synthesized graphitic carbon nitride nanosheets (g‐C3N4 nanosheets) against Pseudomonas syringae pv. tabaci was systematically investigated in vitro and in vivo. RESULTS: The g‐C3N4 nanosheets exhibited remarkable concentration‐dependent and irradiation‐time‐dependent antibacterial properties, and the 0.5 mg mL−1 concentration ameliorated tobacco wildfire disease in host plants. Specifically, under visible irradiation, g‐C3N4 nanosheets produced numerous reactive oxygen species (ROS), supplementing the plentiful extracellular and intracellular ROS in bacteria. After exposing light‐induced g‐C3N4 nanosheets for 1 h, 500 genes were differentially expressed, according to transcriptome analyses. Notably, the expression of genes related 'antioxidant activity' and 'membrane transport' was sharply upregulated, and those related to 'bacterial chemotaxis', 'biofilm formation', 'energy metabolism' and 'cell motility' were downregulated. After exposure for over 2 h, the longer‐time pressure on the target bacteria cause the decreased biofilm formation and flagellum motility, further injuring the cell membranes leading to cytoplasm leakage and damaged DNA, eventually resulting in the bacterial death. Concomitantly, the attachment of g‐C3N4 nanosheets was a synergistic physical antibacterial pathway. The infection capacity assessment also supported the earlier supposition. CONCLUSION: These results provide novel insights into the photocatalytic antibacterial mechanisms of g‐C3N4 nanosheets at the transcriptome level, which are expected to be useful for dissecting the response pathways in antibacterial activities and for improving g‐C3N4‐based photocatalysts practices in plant disease control. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background: Antibacterial photocatalytic therapy has been employed as a promising strategy to combat antibiotic-resistant bacteria in the water disinfection field, especially some non-metal inorganic nanomaterials. However, their antibacterial activities on plant phytopathogens are poorly understood. Here, the photocatalytic antibacterial mechanism of the urea-synthesized graphitic carbon nitride nanosheets (g-C 3 N 4 nanosheets) against Pseudomonas syringae pv. tabaci was systematically investigated in vitro and in vivo., Results: The g-C 3 N 4 nanosheets exhibited remarkable concentration-dependent and irradiation-time-dependent antibacterial properties, and the 0.5 mg mL -1 concentration ameliorated tobacco wildfire disease in host plants. Specifically, under visible irradiation, g-C 3 N 4 nanosheets produced numerous reactive oxygen species (ROS), supplementing the plentiful extracellular and intracellular ROS in bacteria. After exposing light-induced g-C 3 N 4 nanosheets for 1 h, 500 genes were differentially expressed, according to transcriptome analyses. Notably, the expression of genes related 'antioxidant activity' and 'membrane transport' was sharply upregulated, and those related to 'bacterial chemotaxis', 'biofilm formation', 'energy metabolism' and 'cell motility' were downregulated. After exposure for over 2 h, the longer-time pressure on the target bacteria cause the decreased biofilm formation and flagellum motility, further injuring the cell membranes leading to cytoplasm leakage and damaged DNA, eventually resulting in the bacterial death. Concomitantly, the attachment of g-C 3 N 4 nanosheets was a synergistic physical antibacterial pathway. The infection capacity assessment also supported the earlier supposition., Conclusion: These results provide novel insights into the photocatalytic antibacterial mechanisms of g-C 3 N 4 nanosheets at the transcriptome level, which are expected to be useful for dissecting the response pathways in antibacterial activities and for improving g-C 3 N 4 -based photocatalysts practices in plant disease control. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)