LAUSR

BACKGROUND Phytophthora capsici is a destructive plant oomycete pathogen that could lead to devastating losses of food production. Fungicide application is the main way to control plant disease caused by P. capsici. SYP-14288 is a novel fungicide with a unique mode of action and could be used to control a broad range of plant diseases. In this paper, the potential for SYP-14288 resistance in Phytophthora capsici and its resistance mechanism were evaluated. RESULTS Here, the baseline sensitivities of 133 isolates to SYP-14288 were determined and found to conform to a unimodal curve with a mean EC50 value of 0.625 μg/mL. A total of 21 stable SYP-14288-resistant mutants were generated by fungicide adaptation in three sensitive isolates. The fitness of all the mutants was found to be lower than that of the parental isolates. Otherwise, downregulated of various ATPases may confer different resistance levels in P. capsici. Finally, multiple biochemical studies strongly suggest that both the ATP content and electric potential were reduced in SYP-14288-resistant mutants, and as a compensatory mechanism, respiration was facilitated to make up for the energy defect in mutants. CONCLUSION The low fitness of SYP-14288-resistant mutants suggests that the resistance risk of P. capsici to SYP-14288 is low. Resistance may be led by the permeability change of the mitochondrial inner membrane in SYP-14288-resistant isolates, and the lower ATP consumption lifestyle may be the key to the SYP-14288 resistance generated in P. capsici. The current study could benefit the registration and application of the novel fungicide SYP-14288. This article is protected by copyright. All rights reserved.