AimsTo evaluate the effect of carabrone on mitochondrial respiratory chain complexes in Gaeumannomyces graminis to identify carabrone targets. Methods and ResultsThe influence of carabrone on mitochondria in G.graminis mycelia was determined, and the activity of complexes I-V, citrate synthase, and respiratory chain complexes I+III and II+III was evaluated following treatment with 30% effective concentration (EC30) as well as EC50 and EC70 of carabrone for 0, 6, 12 and 24h. Quantitative real-time PCR analysis of the relative expression of genes encoding mitochondrial respiratory chain complexes was then conducted. Carabrone treatment influenced the activity of mitochondrial respiratory chain complexes III, I+III, and II+III in G.graminis in a dose- and time-dependent manner with a marked decrease (c. 50% compared to the control) in mitochondrial respiratory chain complex III activity following treatment with carabrone at the EC50. The GgCyc1 was downregulated following carabrone treatment at the EC50, and the other genes were upregulated with respect to the control. ConclusionsThis study showed that mitochondrial respiratory chain complex III in G.graminis is highly sensitive to carabrone and is a potential target of this botanical fungicidal agent. Significance and Impact of the StudyCarabrone is a promising botanical fungicidal agent that is environmentally friendly and can control plant diseases and reduce chemical fungicides in agricultural production.