Hengwei Qian1, Juan Du2, Mengyu Chi1, Xiaomei Sun3, Wenxing Liang1, Jinguang Huang1, Baodu Li1. 1. College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao, PR China. 2. College of Life Science, Qingdao Agricultural University, Qingdao, PR China. 3. College of Animation and Communication, Qingdao Agricultural University, Qingdao, PR China.
Abstract
BACKGROUND: Fusarium graminearum is the main pathogen of Fusarium head blight (FHB), a worldwide plant disease and one of the most significant wheat diseases in China. Demethylation inhibitor (DMI) fungicides, such as tebuconazole (TEC), are widely used to control FHB, but long-term use leads to low efficacy against FHB. Earlier studies showed that DMI resistance is associated with the fungal sterol 14α-demethylase (cytochrome P450 CYP51) gene, and that point mutations in the CYP51 gene are the primary mechanism of resistance to DMI fungicides. The aims of this study were to clarify the molecular mechanisms of resistance to TEC and identify the binding sites on the FgCYP51B protein. RESULTS: Site-directed mutagenesis was used to change the FgCYP51B gene of wild-type strain PH-1 from tyrosine to histidine at residue 137 (Y137H) to generate a mutant transformant, which was confirmed to be resistant to TEC compared with the parental strains. A three-dimensional FgCYP51B model was constructed, and molecular docking simulation studies were conducted to identify the optimum binding mode with TEC. The wild-type FgCYP51B protein displayed stronger affinity to TEC than that of the mutated FgCYP51B in the molecular docking analysis. CONCLUSION: These results indicate that a Tyr137 amino acid mutation in the cytochrome P450 FgCYP51B could lead to resistance to TEC and that Y137 forms part of the tebuconazole-binding pocket.
BACKGROUND:Fusarium graminearum is the main pathogen of Fusarium head blight (FHB), a worldwide plant disease and one of the most significant wheat diseases in China. Demethylation inhibitor (DMI) fungicides, such as tebuconazole (TEC), are widely used to control FHB, but long-term use leads to low efficacy against FHB. Earlier studies showed that DMI resistance is associated with the fungal sterol 14α-demethylase (cytochrome P450 CYP51) gene, and that point mutations in the CYP51 gene are the primary mechanism of resistance to DMI fungicides. The aims of this study were to clarify the molecular mechanisms of resistance to TEC and identify the binding sites on the FgCYP51B protein. RESULTS: Site-directed mutagenesis was used to change the FgCYP51B gene of wild-type strain PH-1 from tyrosine to histidine at residue 137 (Y137H) to generate a mutant transformant, which was confirmed to be resistant to TEC compared with the parental strains. A three-dimensional FgCYP51B model was constructed, and molecular docking simulation studies were conducted to identify the optimum binding mode with TEC. The wild-type FgCYP51B protein displayed stronger affinity to TEC than that of the mutated FgCYP51B in the molecular docking analysis. CONCLUSION: These results indicate that a Tyr137 amino acid mutation in the cytochrome P450 FgCYP51B could lead to resistance to TEC and that Y137 forms part of the tebuconazole-binding pocket.
Authors: Can Zhang; Muhammad Imran; Min Liu; Zhiwen Li; Huige Gao; Hongxia Duan; Shunli Zhou; Xili Liu Journal: Front Microbiol Date: 2020-06-30 Impact factor: 5.640