Aptly chosen, effectively emphasizing the action and mechanism of antimycin A₁

Rhizoctonia solani Kühn, a plant pathogenic fungus that can cause diseases in multiple plant species is considered one of the common and destructive pathogens in many crops. This study investigated the action of antimycin A_1, which was isolated from Streptomyces AHF-20 found in the rhizosphere soil of an ancient banyan tree, on Rhizoctonia solani and its mechanism. The inhibitory effect of antimycin A₁ on R. solani was assessed using the comparative growth rate method. The results revealed that antimycin A₁ exhibited a 92.55% inhibition rate against R. solani at a concentration of 26.66 μg/mL, with an EC₅₀ value of 1.25 μg/mL. To observe the impact of antimycin A₁ on mycelial morphology and ultrastructure, the fungal mycelium was treated with 6.66 μg/mL antimycin A₁, and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed. SEM analysis demonstrated that antimycin A₁ caused mycelial morphology to become stripped, rough, and folded. The mycelium experienced severe distortion and breakage, with incomplete or locally enlarged ends, shortened branches, and reduced numbers. TEM observation revealed thickened cell walls, indistinct organelle boundaries, swollen mitochondria, exosmotic substances in vesicles, slow vesicle fusion, and cavitation. Real-time quantitative PCR and enzyme activity assays were conducted to further investigate the impact of antimycin A₁ on mitochondria. The physiological and biochemical results indicated that antimycin A₁ inhibited complexes III and IV of the mitochondrial electron transport chain. RT-PCR analysis demonstrated that antimycin A₁ controlled the synthesis of relevant enzymes by suppressing the transcription levels of ATP6, ATP8, COX3, QCR6, CytB, ND1, and ND3 genes in mitochondria. Additionally, a metabolomic analysis revealed that antimycin A₁ significantly impacted 12 metabolic pathways. These pathways likely experienced alterations in their metabolite profiles due to the inhibitory effects of antimycin A₁. Consequently, the findings of this research contribute to the potential development of novel fungicides.