Search

Background: Epicoccum sorghinum is a pathogenic fungus that causes leaf spot in a wide range of plants, including maize, and synthesizes the mycotoxin tenuazonic acid (TEA), which is carcinogenic. Despite the relevant economic and yield losses caused by E. sorghinum worldwide, methods for the control of this pathogen are lacking., Results: In this work, the efficacy of Bacillus-produced dipicolinic acid (DPA) for control of E. sorghinum was evaluated using in vitro and in vivo assays, and compared with the efficacy of three commercial fungicides, including carbendazim, prochloraz, and thiram. DPA inhibited E. sorghinum mycelial growth, and conidia germination, and produced important alterations in E. sorghinum hyphae. Interestingly, 10 mM DPA reduced TEA biosynthesis by 86.6%. Although DPA rapidly degraded on maize leaves, 10 mM DPA showed higher preventive (67.4% lesion length inhibition) and inhibitory (89.5% lesion length inhibition) efficacies for the control of E. sorghinum on maize leaves compared to the commercial fungicides., Conclusions: Collectively, this study presents the first method for the control of E. sorghinum on maize and demonstrates that DPA application is a suitable approach to inhibit E. sorghinum symptoms in plants and TEA biosynthesis. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

Background: p-Aminobenzoic acid (pABA) is an environmentally friendly bioactive metabolite synthesized by Lysobacter antibioticus. This compound showed an unusual antifungal mode of action based on cytokinesis inhibition. However, the potential antibacterial properties of pABA remain unexplored., Results: In this study, pABA showed antibacterial activity against Gram-negative bacteria. This metabolite inhibited growth (EC 50  = 4.02 mM), and reduced swimming motility, extracellular protease activity, and biofilm formation in the soybean pathogen Xanthomonas axonopodis pv. glycines (Xag). Although pABA was previously reported to inhibit fungal cell division, no apparent effect was observed on Xag cell division genes. Instead, pABA reduced the expression of various membrane integrity-related genes, such as cirA, czcA, czcB, emrE, and tolC. Consistently, scanning electron microscopy observations revealed that pABA caused major alternations in Xag morphology and blocked the formation of bacterial consortiums. In addition, pABA reduced the content and profile of outer membrane proteins and lipopolysaccharides in Xag, which may explain the observed effects. Preventive and curative applications of 10 mM pABA reduced Xag symptoms in soybean plants by 52.1% and 75.2%, respectively., Conclusions: The antibacterial properties of pABA were studied for the first time, revealing new insights into its potential application for the management of bacterial pathogens. Although pABA was previously reported to show an antifungal mode of action based on cytokinesis inhibition, this compound inhibited Xag growth by altering the outer membrane's integrity. © 2023 Society of Chemical Industry., (© 2023 Society of Chemical Industry.)

Background: Kiwifruit is highly susceptible to fungal pathogens, such as Botrytis cinerea, which reduce crop production and quality. In this study, dipicolinic acid (DPA), which is one of the main components of Bacillus spores, was evaluated as a new elicitor to enhance kiwifruit resistance to B. cinerea., Results: DPA enhances antioxidant capacity and induces the accumulation of phenolics in B. cinerea-infected 'Xuxiang' kiwifruit. The contents of the main antifungal phenolics in kiwifruit, including caffeic acid, chlorogenic acid and isoferulic acid, increased after DPA treatment. DPA enhanced H 2 O 2 levels after 0 and 1 days, which promoted catalase (CAT) and superoxide dismutase (SOD) activities, reducing long-term H 2 O 2 levels. DPA promoted the up-regulation of several kiwifruit defense genes, including CERK1, MPK3, PR1-1, PR1-2, PR5-1 and PR5-2. Furthermore, DPA at 5 mM inhibited B. cinerea symptoms in kiwifruit (95.1% lesion length inhibition) more effectively than the commercial fungicides carbendazim, difenoconazole, prochloraz and thiram., Conclusions: The antioxidant properties of DPA and the main antifungal phenolics of kiwifruit were examined for the first time. This study uncovers new insights regarding the potential mechanisms used by Bacillus species to induce disease resistance. © 2023 Society of Chemical Industry., (© 2023 Society of Chemical Industry.)

Background: Ceratocystis fimbriata is a hazardous fungal pathogen able to cause black rot disease on sweet potato. The management of C. fimbriata strongly relies on the use of toxic fungicides, and there is a lack of efficient alternative strategies., Results: The antifungal properties of quinolinic acid (QA) were studied for the first time, indicating that QA shows selective antifungal activity against C. fimbriata. QA inhibited completely the mycelial growth of C. fimbriata at less than 0.8 mg mL -1 concentration (pH 4), and was able to produce alterations in the fungal cell wall, and to impede spore agglutination and mycelium formation. QA significantly reduced the concentration of ergosterol, and was able to associate to iron (II), suggesting that QA may be a lanosterol 14-α demethylase inhibitor. In preventive applications, QA reduced the disease incidence of C. fimbriata on sweet potato by 75%, achieving higher control efficacy in comparison with commercial fungicides prochloraz and carbendazim., Conclusions: The first selective antifungal agent against C. fimbriata was discovered in this work, and showed suitable antifungal properties for the management of black rot disease. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Background: Xanthomonas axonopodis pv. glycines (Xag) is a hazardous pathogen able to cause bacterial pustule disease in soybean, reducing crop yield and quality. Although flavonoids rutin and genistein are known to play an important role in soybean defence, soybean is only able to produce Biochanin A in low concentration., Results: In this work, Biochanin A was found to produce higher antibacterial activity against Xag in comparison with genistein (minimum inhibitory concentration < 100 μg/mL). Biochanin A was able to inhibit DNA synthesis and flagella formation in Xag, and altered the composition of the bacterial membrane. These effects reduced swimming motility, extracellular protease activity and biofilm formation. Further, Biochanin A was tested for the control of Xag in soybean leaves, showing similar, or even higher, inhibitory ability in comparison with some products commonly used for the control of this pathogen., Conclusions: The antibacterial properties of Biochanin A against Xag have been studied for the first time, revealing new insights on the potential applications of this isoflavonoid for the management of bacterial pustule disease. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)