A novel target-site mutation (H146Q) outside the ubiquinone binding site of succinate dehydrogenase confers high levels of resistance to cyflumetofen and pyflubumide in Tetranychus urticae

Emre İnak; Sander De Rouck; Berke Demirci; Wannes Dermauw; Sven Geibel; Thomas Van Leeuwen

doi:10.1016/j.ibmb.2024.104127

A novel target-site mutation (H146Q) outside the ubiquinone binding site of succinate dehydrogenase confers high levels of resistance to cyflumetofen and pyflubumide in Tetranychus urticae

Insect Biochem Mol Biol. 2024 Apr 22:170:104127. doi: 10.1016/j.ibmb.2024.104127. Online ahead of print.

Authors

Emre İnak¹, Sander De Rouck², Berke Demirci³, Wannes Dermauw², Sven Geibel⁴, Thomas Van Leeuwen⁵

Affiliations

¹ Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium; Department of Plant Protection, Faculty of Agriculture, Ankara University, 06135, Ankara, Turkey.
² Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
³ Graduate School of Natural and Applied Sciences, Ankara University, 06110, Ankara, Turkey.
⁴ Bayer AG, Crop Science Division, Alfred-Nobel-Straße 50, 40789, Monheim, Germany.
⁵ Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium. Electronic address: thomas.vanleeuwen@ugent.be.

PMID: 38657708
DOI: 10.1016/j.ibmb.2024.104127

Abstract

Mitochondrial electron transfer inhibitors at complex II (METI-II), also referred to as succinate dehydrogenase inhibitors (SDHI), represent a recently developed class of acaricides encompassing cyflumetofen, cyenopyrafen, pyflubumide and cyetpyrafen. Despite their novelty, resistance has already developed in the target pest, Tetranychus urticae. In this study a new mutation, H146Q in a highly conserved region of subunit B of complex II, was identified in a T. urticae population resistant to all METI-IIs. In contrast to previously described mutations, H146Q is located outside the ubiquinone binding site of complex II. Marker-assisted backcrossing of this mutation in a susceptible genetic background validated its association with resistance to cyflumetofen and pyflubumide, but not cyenopyrafen or cyetpyrafen. Biochemical assays and the construction of inhibition curves with isolated mitochondria corroborated this selectivity. In addition, phenotypic effects of H146Q, together with the previously described H258L, were further examined via CRISPR/Cas9 gene editing. Although both mutations were successfully introduced into a susceptible T. urticae population, the H146Q gene editing event was only recovered in individuals already harboring the I260V mutation, known to confer resistance towards cyflumetofen. The combination of H146Q + I260V conferred high resistance levels to all METI-II acaricides with LC₅₀ values over 5000 mg a.i./L for cyflumetofen and pyflubumide. Similarly, the introduction of H258L via gene editing resulted in high resistance levels to all tested acaricides, with extreme LC₅₀ values (>5000 mg a.i./L) for cyenopyrafen and cyetpyrafen, but lower resistance levels for pyflubumide and cyflumetofen. Together, these findings indicate that different mutations result in a different cross-resistance spectrum, probably also reflecting subtle differences in the binding mode of complex II acaricides.

Keywords: Acaricide resistance; CRISPR/Cas9; Complex II inhibitors; H146Q; H258L; I260V; SDHI; SYNCAS; Target-site mutations; sdhB.