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Cytochrome c oxidase (Cox) is a crucial terminal oxidase in the electron transport chain. In this study, we generated 14 Cox gene deletion or overexpression mutants in Fusarium graminearum . Fungicide sensitivity tests revealed that 11 Cox gene deletion mutants displayed resistance to pyraclostrobin, while 10 overexpression mutants showed hypersensitivity. RNA-Seq and RT-qPCR analyses demonstrated the upregulation of FgAox (alternative oxidase in F. graminearum ), FgAod 2, and FgAod 5 (alternative oxidase deficiency in F. graminearum ) in ΔFgCox4-2 and ΔFgCox17-75 mutants. In 11 Cox gene deletion mutants, FgAox expression was significantly upregulated, whereas in 10 Cox gene overexpression mutants, it was significantly downregulated. FgAox overexpression mutants exhibit resistance to pyraclostrobin, while FgAox deletion mutants show hypersensitivity to pyraclostrobin. FgAod2 and FgAod5 were identified as transcription factors for FgAox . Our findings reveal that FgCox influences pyraclostrobin sensitivity by regulating FgAox through FgAod2 and FgAod5. Understanding pyraclostrobin resistance mechanisms in F. graminearum could help develop better fungicide rotation and application strategies to manage resistance and guide the creation of new fungicides targeting different pathways.

Excessive usage of biologically toxic fungicides and their matrix materials poses a serious threat to public health. Leveraging fungicide carriers with inherent pathogen inhibition properties is highly promising for enhancing fungicide efficacy and reducing required dosage. Herein, a series of coacervates have been crafted with lignin and surfactin, both of which are naturally derived and demonstrate substantial antifungal properties. This hierarchically assembled carrier not only effectively loads fungicides with a maximum encapsulation efficiency of 95% but also stably deposits on hydrophobic leaves for high-speed impacting droplets. Intriguingly, these coacervates exhibit broad spectrum fungicidal activity against eight ubiquitous phytopathogens and even act as a standalone biofungicide to replace fungicides. This performance can significantly reduce the fungicide usage and be further strengthened by an encapsulated fungicide. The inhibition rate reaches 87.0% when 0.30 mM pyraclostrobin (Pyr) is encapsulated within this coacervate, comparable to the effectiveness of 0.80 mM Pyr alone. Additionally, the preventive effects against tomato gray mold reached 53%, significantly surpassing those of commercial adjuvants. Thus, it demonstrates that utilizing biosurfactants and biomass with intrinsic antifungal activity to fabricate fully biobased coacervates can synergistically combine the functions of a fungicide carrier and antifungal agent against phytopathogens and guarantee environmental friendliness. This pioneering approach provides deeper insights into synergistically enhancing the effectiveness of agrochemicals from multiple aspects, including fungicide encapsulation, cooperative antifungal action, and droplet deposition.

Plant pathogens have frequently shown multidrug resistance (MDR) in the field, often linked to efflux and sometimes metabolism of fungicides. To investigate the potential role of metabolic resistance in B. cinerea strains showing MDR, the azoxystrobin-sensitive strain B05.10 and -resistant strain Bc242 were treated with azoxystrobin. The degradation half-life of azoxystrobin in Bc242 (9.63 days) was shorter than that in B05.10 (28.88 days). Azoxystrobin acid, identified as a metabolite, exhibited significantly lower inhibition rates on colony and conidia (9.34 and 11.98%, respectively) than azoxystrobin. Bc242 exhibited higher expression levels of 34 cytochrome P450s (P450s) and 11 carboxylesterase genes (CarEs) compared to B05.10 according to RNA-seq analysis. The expression of P450 genes Bcin_02g01260 and Bcin_12g06380 , along with the CarEs Bcin_12g06360 in Saccharomyces cerevisiae , resulted in reduced sensitivity to various fungicides, including azoxystrobin, kresoxim-methyl, pyraclostrobin, trifloxystrobin, iprodione, and carbendazim. Thus, the mechanism of B. cinerea MDR is linked to metabolism mediated by the CarE and P450 genes.

The uptake, translocation, and subcellular distribution of oxathiapiprolin and famoxadone in tomato plants were investigated using hydroponic experiments. Oxathiapiprolin and famoxadone mainly accumulated in the tomato roots with limited translocation capacity from the roots to the upper part. The root absorption and inhibitor results noted the dominance of the apoplastic and symplastic pathways in the oxathiapiprolin and famoxadone uptake by the tomato roots, respectively. Furthermore, the uptake process for the two fungicides followed passive and aquaporin-dependent transport. Insoluble cell components (cell organelles and walls) were the dominant storage compartments for oxathiapiprolin and famoxadone. In the protoplast, oxathiapiprolin in the soluble fraction had a higher proportion than that of famoxadone. Finally, the uptake and distribution of the two fungicides by the tomato plants was accurately predicted using a partition-limited model. Thus, this study provides an in-depth understanding of the transfer of oxathiapiprolin and famoxadone from the environment to tomato plants.

Rice bakanae disease (RBD) caused by Fusarium fujikuroi is a widespread and destructive disease of rice. It is urgent to introduce a new class of fungicide to manage the fungicidal resistance problem and effectively control the disease. Azoxystrobin (AZO) is an active fungicide with a broad antifungal spectrum, while its activity against F . fujikuroi is not well investigated. In this study, the baseline sensitivity of F . fujikuroi to AZO was established by testing the sensitivity of 100 isolates, collected from Anhui Province of China. The mechanism of resistance to AZO was also investigated. AZO exhibited a strong activity against the 100 F . fujikuroi isolates with EC 50 values of 0.822 ± 0.285 and 0.762 ± 0.283 μg/mL for mycelial growth and conidial germination, respectively, and both of the baseline sensitivity curves were validated as unimodal curves. To investigate the resistance mechanism, six mutants with resistance factor (RF) values >50 were generated from wild-type sensitive strains through UV mutagenesis, and sequence analysis showed that mutation G143A in cyt b conferred the resistance to AZO. Mycelial growth, conidia production, pathogenicity, and ATP production were decreased in all six resistant mutants as compared to the parental strains, indicating the fitness penalties in this phenotype of resistance mutation. In addition, the cross-resistance assay showed that there was no cross-resistance between AZO and carbendazim, prochloraz, phenamacril, or pydiflumetofen. AZO can be an efficient candidate to control RBD in China with moderate to low fungal resistance risk, but continuous resistance monitoring should be performed during the application of this fungicide.

Seed treatment with fungicides has been regarded as a principal, effective, and economic technique for soybean [ Glycine max (L.) Merr .] against pathogenic microorganisms during seed germination and seedling growth. Investigation of the characteristics of seed-treatment reagents is an indispensable basis for their application. The aim of the present work is to evaluate the use of pyraclostrobin as an ingredient for soybean seed treatment by investigating its accumulation-dissipation kinetics in plants, plant-growth activation, and protection against Phytophthora sojae . The results showed that the pyraclostrobin stimulated the visible growth (root and shoot length) of soybean plants, increased the chlorophyll level and root activity, and lowered the malonaldehyde (MDA) level. The peak level and bioavailability of pyraclostrobin in soybean roots were 19.9- and 33.2-fold those in leaves, respectively, indicating that pyraclostrobin was mainly accumulated in roots. Pyraclostrobin had a continuous positive effect on the flavonoid levels and the phenylalanine ammonialyase (PAL) activity in roots and leaves, which could enhance the plant defense system. Pyraclostrobin showed in vitro toxicity to P. sojae with a half-inhibition concentration (EC 50 ) of 1.59 and 1.24 μg/mL for pyraclostrobin and pyraclostrobin plus salicylhydroxamic acid (SHAM, an inhibitor of the alternative pathway of respiration), respectively. Seed treatment with pyraclostrobin significantly reduced the severity of Phytophthora root rot, with a control efficacy of 60.7%. To the best of our knowledge, this is the first report on the characteristics of pyraclostrobin used in soybean seed treatment and its efficacy against Phytophthora root rot.

Pyraclostrobin (PYR) is a commonly used strobilurin fungicide, which inhibits mitochondrial respiration at the ubiquinol oxidation center site of the cytochrome bc1 complex. Little information is available regarding the crystal structure of PYR on its fungicidal effect. In this study, the crystal structures of eight PYRs (PYR-A to H) from different sources are determined by using high-resolution X-ray powder diffraction (XRPD) and model construction with the Pawley refinement module. The effects of PYRs on mycelium growth, the kinetics of mycelial growth, conidial germination, and tube elongation of conidia of Botrytis cinerea from tomato are compared. The level of organic acids in the mitochondrial tricarboxylic acid cycle of PYR-treated B. cinerea is analyzed. The results show that PYR-A to PYR-H have their own unique character of XRPD patterns, but the crystal morphology of eight PYRs presents in the triclinic crystal system and space group P 1̅. PYR-D with the eclipsed conformation and rational edge angles α (72.599°) and β (98.612°) in the crystal cell shows the highest inhibitory effect against mycelium growth with EC 50 as 3.383 μg mL -1 , the best time-dependent effects on the mycelium growth kinetics, and the strongest inhibition on tube elongation of conidia, whereas PYR-E with anticonformation is the worst. Moreover, a significant accumulation of fumarate, malate, and oxalate in the PYR-D-treated mycelium is observed. These findings reinforce the need for a definite crystal structure of PYR to limit usage and mitigate future selection pressure for gray mold management.

In this study, three types of pyraclostrobin formulations (including emulsifiable concentrate (EC), suspension concentrate (SC), and microcapsules (MCs)) were used to control cucumber anthracnose. Pyraclostrobin EC had the highest inhibitory activity against Colletotrichum orbiculare in vitro. Much different from the bioactivity in vitro, pyraclostrobin MCs exhibited the highest control efficacy on cucumber anthracnose both in pot and field experiments. The physicochemical properties (particle size, surface tension) of the spray dilution, their interaction with target leaves (contact angle, adhesional tension, work of adhesion, retention, crystallization) and dissipation dynamic of the active ingredient were found to be highly potential factors that would significantly influence the control efficacy of pesticide formulations. Results showed that the control efficacies of different formulations of pyraclostrobin were determined mainly by the final behavior of the pesticides at the target interface, namely, the retention, crystallization, and dissipation dynamics of active ingredients. This study had revealed crucial factors that would influence the efficacy of different formulations of pyraclostrobin and thus could guide the rational and efficient use of different formulations of pesticides on target crops.

The hydrophobic wax layer of pepper fruit (Capsicum frutescens L.) increases the importance of selecting adjuvants that improve the wetting property of droplets on the target organism and increase the effective utilization of fungicides. In this study, the effect of adjuvants including nonionic, cationic, organosilicone, and oils on the wettability of fungicides was determined. The critical micelle concentrations for S903 (organosilicone), 1227 (cationic), AEO-5 (nonionic), GY-Tmax (oil), and XP-2 (oil) were 25, 1000, 100, 200, and 500 mg/L, respectively. Interface behaviors and in vivo tests suggested that adjuvants at appropriate concentrations (S903, 2.5 mg/L; 1227, 100 mg/L; AEO-5, 1 mg/L; GY-Tmax, 50 mg/L; and XP-2, 5 mg/L) resulted in optimum efficiency. Adjuvants significantly increased the inhibitory activity of pyraclostrobin against the mycelial growth, spore germination, and germ tube elongation of Colletotrichum scovillei by 41.3-58.8%, 28.2-44.6%, and 27.8-39.8%, respectively. Pyraclostrobin amended with S903 and XP-2 showed higher efficacy against anthracnose than the fungicide alone on pepper fruit. The increased efficacy may have resulted from the changed crystal morphology (ellipses of similar sizes), improved wettability, and rainfastness. A structural equation model indicated that surface tension and retention play the most important roles in the application properties of fungicide. In field experiments, the efficacy of pyraclostrobin with adjuvants showed no significant difference with pyraclostrobin alone, which indicated that, except for adjuvants, other spraying technologies are important for improving the field performance of fungicides. These results provide a foundation for the synthesis of highly efficient fungicides based on crystal structure and for the sustainable management of pepper anthracnose.

Slow-release fungicide formulations (azoxystrobin, epoxiconazole, and tebuconazole) shaped as pellets and granules in a matrix of biodegradable poly(3-hydroxybutyrate) and natural fillers (clay, wood flour, and peat) were constructed. Infrared spectroscopy showed no formation of chemical bonds between components in the experimental formulations. The formulations of pesticides had antifungal activity against Fusarium verticillioides in vitro . A study of biodegradation of the experimental fungicide formulations in the soil showed that the degradation process was mainly influenced by the type of formulation without significant influence of the type of filler. More active destruction of the granules led to a more rapid accumulation of fungicides in the soil. The content of fungicides present in the soil as a result of degradation of the formulations and fungicide release was determined by their solubility. Thus, all formulations are able to function in the soil for a long time, ensuring gradual and sustained delivery of fungicides.

A series of dithioacetal derivatives bearing a strobilurin moiety were designed and synthesized on the basis of our previous work. The antiviral activities of these compounds against Potato virus Y (PVY), Cucumber mosaic virus (CMV), and Tobacco mosaic virus (TMV) were systematically evaluated. Bioassay results indicated that C14 elicited excellent curative and protective activities against PVY, CMV, and TMV. The former had 50% effective concentrations (EC 50 ) of 125.3, 108.9, and 181.7 μg/mL, respectively, and the latter had 148.4, 113.2, and 214.6 μg/mL, respectively, which were significantly superior to those of lead compound 6f (297.6, 259.6, and 582.4 μg/mL and 281.5, 244.3, and 546.3 μg/mL, respectively), Ningnanmycin (440.5, 549.1, and 373.8 μg/mL and 425.3, 513.3, and 242.7 μg/mL, respectively), Chitosan oligosaccharide (553.4, 582.8, and 513.8 μg/mL and 547.3, 570.6, and 507.9 μg/mL, respectively), and Ribavirin (677.4, 690.3, and 686.5 μg/mL and 652.7, 665.4, and 653.4 μg/mL, respectively). Moreover, defensive enzyme activities and RT-qPCR analysis demonstrated that the antiviral activity was associated with the changes of SOD, CAT, and POD activities in tobacco, which was proved by the related proteins of abscisic acid signaling pathway. This work provided a basis for further design, structural modification, and development of dithioacetal derivatives as new antiviral agents.

The yam (Dioscorea spp.) is widely cultivated in China. The degradation of dithianon and pyraclostrobin in yams with different planting and processing treatments was investigated in this article. An analytical method for two pesticides in yam and yam plant was developed, and recoveries were between 77% and 93%, with relative standard deviations from 0.8% to 7.4%, respectively. On the basis of this method, half-lives for plants grown on stakes versus plants grown without stakes were compared. The results indicated that the half-life for pesticide residues for plants grown on stakes versus plants grown without stakes differed as 6.7 versus 3.1 days for dithianon and 5.4 versus 5.2 days for pyraclostrobin. Dithianon was significantly influenced by planting mode because of its low stability under sunlight. The processing factors of various processing treatments (hot air-drying, vacuum freeze-drying, microwave vacuum-drying, infrared-drying, steaming, and boiling) were all <1, indicating that those processes can reduce residues of two pesticides at different levels. Significant amounts of residues were removed during the boiling treatment, whereas the others showed less effect.