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.
Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
Insect Biochem Mol Biol. 2024 Jul;170:104127. doi: 10.1016/j.ibmb.2024.104127. Epub 2024 Apr 22.
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 LC 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 LC 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.
线粒体电子传递抑制剂复合物 II（METI-II），也称为琥珀酸脱氢酶抑制剂（SDHI），是一类最近开发的杀螨剂，包括氟吡呋喃酮、氰氟虫腙、唑螨酯和环丙嘧啶。尽管它们是新的，但靶标害虫桃蚜已经产生了抗性。在这项研究中，在对所有 METI-II 都具有抗性的桃蚜种群中，发现了复合物 II 亚基 B 高度保守区域的一个新突变 H146Q。与以前描述的突变不同，H146Q 位于复合物 II 的泛醌结合位点之外。在易感遗传背景下对该突变进行标记辅助回交，验证了其与氟吡呋喃酮和唑螨酯抗性的关联，但与氰氟虫腙或环丙嘧啶无关。用分离的线粒体进行生化测定和抑制曲线构建证实了这种选择性。此外，还通过 CRISPR/Cas9 基因编辑进一步研究了 H146Q 的表型效应以及之前描述的 H258L。尽管这两种突变都成功地引入了易感桃蚜种群，但只有在已经携带已知对氟吡呋喃酮具有抗性的 I260V 突变的个体中才恢复了 H146Q 基因编辑事件。H146Q + I260V 的组合对所有 METI-II 杀螨剂表现出高抗性水平，氟吡呋喃酮和唑螨酯的 LC 值超过 5000 mg a.i./L。同样，通过基因编辑引入 H258L 也导致对所有测试杀螨剂的高抗性水平，氰氟虫腙和环丙嘧啶的极端 LC 值（>5000 mg a.i./L），但对氟吡呋喃酮和唑螨酯的抗性水平较低。总之，这些发现表明不同的突变导致不同的交叉抗性谱，这可能也反映了复合物 II 杀螨剂结合模式的细微差异。
