Tebuconazole resistance of <i>Fusarium graminearum</i> field populations from wheat in Henan Province

Abstract

Abstract Fusarium head blight (FHB) is caused by Fusarium graminearum , which contributes serious economic losses to crop yields, and is an epidemic disease of wheat. The resistance to tebuconazole of 1,118 F . graminearum strains obtained from different areas of Henan Province in 2018–2020 was determined by the discriminatory doses of 5.0 μg/ml. A total of 362 F . graminearum strains resistant to tebuconazole were detected, and the frequency of resistance of F. graminearum strains to tebuconazole was 30.7%. The EC 50 and EC 90 values of F. graminearum strains to tebuconazole were calculated according to the mycelial growth inhibition of the Henan F. graminearum population. The range of EC 50 values of 756 sensitive strains and 362 resistant strains were 0.01–0.69 and 0.02–3.31 μg/ml, and the average ± SD EC 50 of sensitive and resistant strains were 0.13 ± 0.01 and 0.40 ± 0.13 μg/ml. The range of EC 90 values of 756 sensitive strains and 362 resistant strains were 0.31–4.89 and 0.65–18.69 μg/ml, and the average ± SD EC 90 values were 1.13 ± 0.05 and 2.98 ± 0.09 μg/ml. The CYP51A and CYP51B genes of the sensitive and resistant strains were amplified separately by polymerase chain reaction (PCR) and analysed. The results showed that among the 150 resistant strains, only six resistant strains had amino acid mutation, which changed from serine to tyrosine (TCA‐TAT, Ser‐Tyr) at position 169 of CYP51B gene, and no amino acid mutation was found in CYP51B of the other 144 resistant strains. No amino acid mutation was found in the CYP51A gene of 150 resistant strains. These results provide important information to growers for monitoring tebuconazole resistance in F. graminearum field populations from wheat in Henan Province.