The Effect of (1S,2R-((3-bromophenethyl)amino)-N-(4-chloro-2-trifluoromethylphenyl) cyclohexane-1 -sulfonamide) on Botrytis cinerea through the Membrane Damage Mechanism

Physiological and Biochemical Responses of Sagittaria trifolia L. to Phytotoxic Ethyl Acetate Fungal Extract from Curvularia lunata Strain CLST-01

Curvularia lunata (No. CLST-01), a fungal pathogen isolated from the threeleaf arrowhead (Sagittaria trifolia L.), has been proposed as a potential mycoherbicide for grass weeds. This paper investigated the physiological and biochemical effects of CLST-01 phytotoxic ethyl acetate fungi extract on the leaves of the threeleaf arrowhead. The results showed that the ethyl acetate fungi extract from CLST-01 can accelerate damage to the cell membrane, increase the production of malondialdehyde, and damage the cellular structure, which could decrease the number of chloroplasts after 96 h treatments. In addition, the content of chlorophyll was reduced by 49.5%, and the net photosynthetic rate, stomatal conductance, and transpiration rate were inhibited. The rates of inhibition were 90.13%, 83.74%, and 79.31%, respectively, and the intercellular CO₂ concentration increased by 51.87% on Day 9 after treatment with a concentration of 200 μg/mL. In summary, the phytotoxic ethyl acetate fungal extract from C. lunata CLST-01 can inhibit the photosynthesis of the threeleaf arrowhead leaves, destroy the ultrastructure of leaves, and affect the growth of this invasive weed. Therefore, it has the potential to be developed into a mycoherbicide for weed control in crops as a natural photosynthetic inhibitor.

Novel Sulfonamide Derivatives Containing a Piperidine Moiety as New Bactericide Leads for Managing Plant Bacterial Diseases

Plant bacterial diseases are an intractable problem due to the fact that phytopathogens have acquired strong resistances for traditional pesticides, resulting in restricting the quality and yield of agricultural products around the world. To develop new agrochemical alternatives, we prepared a novel series of sulfanilamide derivatives containing piperidine fragments and assessed their antibacterial potency. The bioassay results revealed that most molecules displayed excellent in vitro antibacterial potency towards Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas axonopodis pv. citri (Xac). In particular, molecule C₄ exhibited outstanding inhibitory activity toward Xoo with EC₅₀ value of 2.02 µg mL^-1, which was significantly better than those of the commercial agents bismerthiazol (EC₅₀ = 42.38 µg mL^-1) and thiodiazole copper (EC₅₀ = 64.50 µg mL^-1). A series of biochemical assays confirmed that compound C₄ interacted with dihydropteroate synthase, and irreversibly damaged the cell membrane. In vivo assays showed that the molecule C₄ presented acceptable curative and protection activities of 34.78% and 39.83%, respectively, at 200 µg mL^-1, which were greater than those of thiodiazole and bismerthiazol. This study highlights the valuable insights for the excavation and development of new bactericides that can concurrently target dihydropteroate synthase and bacterial cell membranes.

An innovative strategy to control Microcystis growth using tea polyphenols sustained-release particles: preparation, characterization, and inhibition mechanism

Allelochemicals have been shown to inhibit cyanobacterial blooms for several years. In view of the disadvantages of "direct-added" mode, natural and pollution-free tea polyphenolic allelochemicals with good inhibitory effect on cyanobacteria were selected to prepare sustained-release particles by microcapsule technology. Results showed that the encapsulation efficiency of tea polyphenols sustained-release particles (TPSPs) was 50.6% and the particle size ranged from 700 to 970 nm, which reached the nanoscale under optimum preparation condition. Physical and chemical properties of TPSPs were characterized to prove that tea polyphenols were well encapsulated and the particles had good thermal stability. The optimal dosage of TPSPs was determined to be 0.3 g/L, at which the inhibition rate on Microcystis aeruginosa in logarithmic growth period could be maintained above 95%. Simultaneous decrease in algal density and chlorophyll-a content indicated that the photosynthesis of algal cells was affected leading to cell death. Significant changes of antioxidant enzyme activities suggested that Microcystis aeruginosa's antioxidant systems had been disrupted. Furthermore, TPSPs increased the concentration of O^2- which led to lipid peroxidation of cell membrane and a subsequent increase in malondialdehyde (MDA) content. Meanwhile, the protein content, nucleic acid content, and electrical conductivity in culture medium rose significantly indicating the cell membrane was irreversibly damaged. This work can provide a basis for the utilization of environmentally friendly algal suppressants.

Novel (Z)/(E)-1,2,4-triazole derivatives containing oxime ether moiety as potential ergosterol biosynthesis inhibitors: design, preparation, antifungal evaluation, and molecular docking

Inspired by the highly effective and broad-spectrum antifungal activity of ergosterol biosynthesis inhibitions, a series of novel 1,2,4-triazole derivatives containing oxime ether moiety were constructed for screening the bioactivity against phytopathogenic fungi. The (Z)- and (E)-isomers of target compounds were successfully separated and identified by the spectroscopy and single crystal X-ray diffraction analyses. The bioassay results showed that the (Z)-isomers of target compounds possessed higher antifungal activity than the (E)-isomers. Strikingly, the compound (Z)-5o exhibited excellent antifungal activity against Rhizoctonia solani with the EC₅₀ value of 0.41 μg/mL in vitro and preventive effect of 94.58% in vivo at 200 μg/mL, which was comparable to the positive control tebuconazole. The scanning electron microscopy observation indicated that the compound (Z)-5o caused the mycelial morphology to become wizened and wrinkled. The molecular docking modes of (Z)-5o and (E)-5o with the potential target protein RsCYP51 were especially compared. And the main interactions between ligands and amino acid residues were carefully analyzed to preliminarily explain the mechanism leading to the difference of activity between two isomers. The study provided a new lead molecular skeleton for developing novel triazole fungicides targeting ergosterol biosynthesis.

Semi-Synthesis of Chloroxaloterpin A and B and Their Antifungal Activity against Botrytis cinerea

Chloroxaloterpin A (1) and B (2) are two diterpenoids with potent inhibitory activities against spore germination of Botrytis cinerea, which were identified from Streptomyces sp. SN194 as minor products previously. In order to overcome the poor yields, 1 and 2 were synthesized using viguiepinol (3), the major metabolite of Streptomyces sp. SN194, as the precursor compound. Scanning electron microscope and transmission electron microscope observations revealed that after treating B. cinerea spores with 1 and 2, spores were obviously aberrant, the cytoplasm appeared withdrawn, and plasma membranes were blurred. Propidium iodide fluorescence assay indicated that 1 and 2 damaged plasma membranes of B. cinerea spores. In vivo assays showed that compounds 1 and 2 could effectively inhibit the sporulation of B. cinerea on tomato fruits, with sporulation inhibitory rates reaching 98.8% at 100 μg/mL. These findings provide new insights into chloroxaloterpin A and B and demonstrate their potential as lead candidates for novel fungicides.

Preliminary Study of Resistance Mechanism of Botrytis cinerea to SYAUP-CN-26

SYAUP-CN-26 (1S, 2R-((3-bromophenethyl)amino)-N-(4-chloro-2-trifluoromethylphenyl) cyclohexane-1-sulfonamide) is a novel sulfonamide compound with excellent activity against Botrytis cinerea. The present study sought to explore the mutant of B.cinerea resistant to SYAUP-CN-26 using SYAUP-CN-26 plates. Moreover, the cell membrane functions of B.cinerea, histidine kinase activity, relative conductivity, triglyceride, and cell membrane structure were determined, and the target gene histidine kinase Bos1 (AF396827.2) of procymidone was amplified and sequenced. The results showed that compared to the sensitive strain, the cell membrane permeability, triglyceride, and histidine kinase activity of the resistant strain showed significant changes. The relative conductivity of the sensitive strain increased by 6.95% and 9.61%, while the relative conductivity of the resistant strain increased by 0.23% and 1.76% with 26.785 µg/mL (EC₉₅) and 79.754 µg/mL (MIC) of SYAUP-CN-26 treatment. The triglyceride inhibition rate of the resistant strain was 23.49% and 37.80%, which was 0.23% and 1.76% higher than the sensitive strain. Compared to the sensitive strain, the histidine kinase activity of the resistant strain was increased by 23.07% and 35.61%, respectively. SYAUP-CN-26 significantly damaged the cell membrane structure of the sensitive strain. The sequencing of the Bos1 gene of the sensitive and resistant strains indicated that SYAUP-CN-26 resistance was associated with a single point mutation (P348L) in the Bos1 gene. Therefore, it was inferred that the mutant of B.cinerea resistant to SYAUP-CN-26 might be regulated by the Bos1 gene. This study will provide a theoretical basis for further research and development of sulfonamide compounds for B. cinerea and new agents for the prevention and control of resistant B. cinerea.

Primary Mode of Action of the Novel Sulfonamide Fungicide against Botrytis cinerea and Field Control Effect on Tomato Gray Mold

Botrytis cinerea is considered an important plant pathogen and is responsible for significant crop yield losses. With the frequent application of commercial fungicides, B. cinerea has developed resistance to many frequently used fungicides. Therefore, it is necessary to develop new kinds of fungicides with high activity and new modes of action to solve the increasingly serious problem of resistance. During our screening of fungicide candidates, one novel sulfonamide compound, N-(2-trifluoromethyl-4-chlorphenyl)-2-oxocyclohexyl sulfonamide (L13), has been found to exhibit good fungicidal activity against B. cinerea. In this work, the mode of action of L13 against B. cinerea and the field control effect on tomato gray mold was studied. L13 had good control against B. cinerea resistant to carbendazim, diethofencarb, and iprodione commercial fungicides in the pot culture experiments. SEM and TEM observations revealed that L13 could cause obvious morphological and cytological changes to B. cinerea, including excessive branching, irregular ramification or abnormal configuration, and the decomposition of cell wall and vacuole. L13 induced more significant electrolyte leakage from hyphae than procymidone as a positive control. L13 had only a minor effect on the oxygen consumption of intact mycelia, with 2.15% inhibition at 50 μg/mL. In two locations over 2 years, the field control effect of L13 against tomato gray mold reached 83% at a rate of 450 g ai ha⁻¹, better than the commercial fungicide of iprodione. Moreover, toxicological tests demonstrated the low toxicological effect of L13. This research seeks to provide technical support and theoretical guidance for L13 to become a real commercial fungicide.