Mechanism of Action of Novel Pyrazole Carboxamide Containing a Diarylamine Scaffold against Rhizoctonia solani

Abstract

In the last few decades, Rhizoctonia solani causing rice sheath blight has resulted in a lot of economic losses in the world. Therefore, many novel pyrazole carboxamide fungicides have been intensively researched and employed to fight against it. In this regard, in recent years, our group reported a novel pyrazole carboxamide containing a diarylamine scaffold with good antifungal activity against rice sheath blight in the pot test and field trial. Following this project, the antifungal mechanism of action of the pyrazole carboxamide has been elucidated in this work. The antifungal result showed that compound SCU2028, N-[2-[(3chlorophenyl)amino]-phenyl]-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxamide, was equivalent to the commercial fungicide thifluzamide and its EC 50 value was 0.022 mg/L against R. solani. Also, the observation results by scanning electron microscopy and transmission electron microscopy showed that it could destroy the fungus' cell walls or membranes and result in the leakage of contents and increase of the number of mitochondria and abnormal morphology. Meanwhile, the result on the mitochondrial membrane potential (MMP) showed that it could decrease R. solani's MMP. Furthermore, the results by label-free quantitative proteomic analysis showed that 1153 proteins were found after R. solani was treated with compound SCU2028, including 212 proteins in the control group and 257 proteins in the treatment group. A total of 142 differential proteins were obtained, of which 92 proteins were upregulated and 50 proteins were downregulated. The differentially expressed proteins affected a series of physiological and biochemical pathways in the mitochondria, endoplasmic reticulum, ribosome, and other related GO and KEGG pathways. In particular, the inhibition of the respiratory chain caused by the TCA cycle and oxidative phosphorylation KEGG pathway indicated that complex II (succinate dehydrogenase) and complex IV (cytochrome oxidase) might be compound SCU2028's main action targets. In addition, multiple experiments of qRT-PCR, enzyme activity detection, and molecular docking confirmed complex II and complex IV as targets. It could be seen that these findings provided a theoretical support for further research and development of the pyrazole carboxamide fungicides.

Activity of the Novel Fungicide SYP-34773 against Plant Pathogens and Its Mode of Action on Phytophthora infestans

“…For instance, the increase of the cell membrane permeability may be caused by ultrastructure damages in cell walls or cytomembrane structures. Another research found that a compound probably targeting respiratory electron transport players could also destroy the cell walls or membranes of R. solani . This might be a similar mechanism that ultrastructure was damaged in our study.…”

“…Another research found that a compound probably targeting respiratory electron transport players could also destroy the cell walls or membranes of R. solani. 37 This might be a similar mechanism that ultrastructure was damaged in our study. In addition, exogenously supplemented ATP could weaken the inhibitory activity of SYP-34773 against P. infestans to certain degrees, especially for zoospore release and cyst germination.…”

Pine Rosin as a Valuable Natural Resource in the Synthesis of Fungicide Candidates for Controlling Fusarium oxysporum on Cucumber

“…DMSO was used as the blank control. The morphology and ultrastructure of mycelia were observed by a scanning electron microscope (Hitachi, Ltd., Tokyo, Japan) and a transmission electron microscope (JEOL, Ltd., Tokyo, Japan). , …”

“…The morphology and ultrastructure of mycelia were observed by a scanning electron microscope (Hitachi, Ltd., Tokyo, Japan) and a transmission electron microscope (JEOL, Ltd., Tokyo, Japan). 9,20 Effect of Compound 3e on the Cell Membrane Permeability of F. oxysporum. The effect of compound 3e on the permeability of the cell membrane of F. oxysporum was determined by the conductivity method.…”

Discovery of zeylenone from Uvaria grandiflora as a potential botanical fungicide

“…2.12 Effects of zeylenone on the mycelium ultrastructure of Phytophthora capsici by transmission electron microscopy Zeylenone was mixed with potato dextrose broth (PDB) medium to make the final concentration of 7 μg mL −1 , and the corresponding solvent was used as the control. The Phytophthora Phytophthora capsici plugs were cultured with shaking at 25 °C, 120 rpm for 72 h. 30 The mycelium samples were fixed in 4% glutaraldehyde buffer fixation solution at 4 °C overnight, and washed three times in 0.1 mol L −1 phosphate-buffered saline (PBS) buffer (pH 7.0) for 15 min each time. 31 Then the mycelium samples were dissolved in 1% osmium tetroxide buffer fixative solution at room temperature and fixed for 2 h. The mycelium samples were washed four times with 0.1 mol L −1 PBS buffer (pH 7.0) for 10 min each time.…”