P-108 - Sensitivity of Fusarium solani species complex from passion fruit to fungicides and mechanism of QoIs resistance

Fusarium solani species complex (FSSC) is an environmental pathogen affecting plants, animals, and humans. To be plant pathogen, FSSC can infect various economical crops. In Taiwan, plant diseases caused by FSSC are commonly observed in cucurbit fruit rot, Phalaenopsis yellow leaf disease, passion fruit collar and fruit rot, and chrysanthemum stem rot, which lead to significant agricultural losses, so it is a crucial issue to manage the diseases caused by FSSC. Chemical control is a common management method for passion fruit diseases. This study focused on FSSC isolates causing passion fruit collar and fruit rot, testing their sensitivity to commonly used fungicides in the field in Taiwan. The sensitive test of fungicides showed that FSSC isolates from passion fruit were higher sensitivity to Tebuconazole and Cyprodinil+Fludioxonil than other fungicides. In this study, most of FSSC isolates were low sensitivities to Quinone outside respiration inhibitors (QoIs), including azoxystrobin, pyraclostrobin and trifloxystrobin. At different temperatures, most FSSC isolates exhibited the highest sensitivity at 32°C. Here, the effect of Alternative Oxidase (AOX) activity on QoIs resistance were carried out. The AOX activity inhibitor, salicylhydroxamic acid (SHAM), was added in medium mixed with three QoIs to confirm whether AOX could reduce the resistance to QoIs. Results demonstrated when the AOX activity was inhibited that the QoIs-resistant FSSC isolates showed more sensitivity to QoIs. Thus, AOX plays one of important role to affect the sensitivity of FSSC isolates to QoIs.