Change in the Sensitivity to Propiconazole of Fusarium graminearum Species Complex Causing Head Blight of Barley and Wheat in Jeolla Province

Jiseon  Baek1   Ju-Young  Nah1   Mi-Jeong  Lee1   Su-Bin  Lim1   Jung-Hye  Choi1   자영 장1   Theresa Lee1   Hyo-Won  Choi2   Jeomsoon Kim1,*   

1Microbial Safety Division, National Institute of Agricultural Sciences, Wanju 55365, Korea

Abstract

Fusarium head blight is an important disease of small grains. It is mainly caused by members of the Fusarium graminearum species complex (FGSC). Barley and wheat growers spray fungicides, especially demethylation-inhibitor fungicides, to suppress the disease. The objective of this study was to examine the changes in the sensitivity of the FGSC population to the triazole fungicide, propiconazole. A total of 124 and 350 isolates of FGSC were obtained from barley and wheat in Jeolla Province during 2010-2016 and 2020-2021, respectively. The species identity and trichothecene chemotypes of the FGSC isolates were determined based on polymerase chain reaction assays targeting translation elongation factor 1-alpha and TRI12 genes, respectively. Sensitivity to propiconazole was determined based on the effective concentration that reduced 50% of the mycelial growth (EC50) using the agar dilution method. Of all isolates, F. asiaticum with the nivalenol chemotype was the most common (83.9% in 2010-2016 and 96.0% in 2020-2021), followed by F. asiaticum with the 3-acetyl deoxynivalenol chemotype (12.1% in 2010-2016 and 2.9% in 2020-2021). The EC50 values of the isolates collected in 2010-2016 and 2020-2021 ranged from 0.0180 to 11.0166 μg/mL and 1.3104 to 17.9587 μg/mL, respectively. The mean EC50 value of the isolates increased from 3.8648 μg/mL in 2010-2016 to 5.9635 μg/mL in 2020-2021. The baseline resistance to propiconazole was determined to be 7 μg/mL, based on the EC50 value of isolates collected in 2010-2016, and the ratio of resistant isolates increased from 9.7% in 2010-2016 to 28.6% in 2020-2021.

Figures & Tables

Fig. 1. Variation of 50% effective concentration (EC) values of species complex isolated from barley and wheat in 2010-2016 and 2020-2021.