LAUSR

Glomerella leaf spot (GLS) caused by Glomerella cingulata is a newly emerging disease that results in severe defoliation and fruit spots in apples. In China, the compound of pyraclostrobin and tebuconazole was registered to control GLS in 2018 and has achieved excellent control efficiency. In this study, we showed that the high-level resistant isolates of G. cingulata to pyraclostrobin, caused by the point mutation at codon 143 (GGT→GCT, G143A) in cytochrome b gene, has appeared in apple orchards in Shandong province in 2020, and the resistance frequency was 4.8%. Based on the genotype of the resistant isolates, we developed a loop-mediated isothermal amplification (LAMP) assay for detection of the pyraclostrobin resistance. The LAMP assay was demonstrated to have good specificity, sensitivity and repeatability, and exhibited high accuracy to detect pyraclostrobin resistance in the field. This study reported the resistance status of GLS to pyraclostrobin in Shandong province, and developed a molecular tool for the detection of pyraclostrobin resistance, which is of practical significance for the scientific control of GLS.