G143A Mutation Conferring Resistance to Quinone Outside Inhibitor Fungicides Detected in Both Podosphaera xanthii and Erysiphe vignae Causing Powdery Mildew on Mung Bean ( Vigna radiata ) in Australia

Abstract

Powdery mildew of mung bean ( Vigna radiata) is caused by two species in Australia: Podosphaera xanthii and Erysiphe vignae. Currently, two fungicides are permitted for managing this disease in Australia: azoxystrobin and tebuconazole. The commercial fungicide products used for mung bean powdery mildew management contain either tebuconazole alone or a mixture of azoxystrobin and tebuconazole. This study detected the G143A mutation in the mitochondrial cytochrome b gene of both P. xanthii and E. vignae. The mutation was detected in two P. xanthii and one E. vignae populations out of a total of 15 populations sampled in southeast Queensland from 2017 to 2024. The G143A mutation is the major DNA marker of resistance to quinone outside inhibitor (QoI) fungicides, including azoxystrobin. This study confirmed that some populations of both powdery mildew species have developed QoI resistance in Australian mung bean fields.