Whole-genome sequencing reveals that mutations in myosin-5 confer resistance to the fungicide phenamacril in Fusarium graminearum

Abstract

To determine the mechanism of resistance to the fungicide phenamacril (JS399-19) in Fusarium graminearum, the causal agent of Fusarium head blight, we sequenced and annotated the genome of the resistant strain YP-1 (generated by treating the F. graminearum reference strain PH-1 with phenamacril). Of 1.4 million total reads from an Illumina-based paired-end sequencing assay, 92.80% were aligned to the F. graminearum reference genome. Compared with strain PH-1, strain YP-1 contained 1,989 single-nucleotide polymorphisms that led to amino acid mutations in 132 genes. We sequenced 22 functional annotated genes of another F. graminearum sensitive strain (strain 2021) and corresponding resistant strains. The only mutation common to all of the resistant mutants occurred in the gene encoding myosin-5 (point mutations at codon 216, 217, 418, 420, or 786). To confirm whether the mutations in myosin-5 confer resistance to phenamacril, we exchanged the myosin-5 locus between the sensitive strain 2021 and the resistant strain Y2021A by homologous double exchange. The transformed mutants with a copy of the resistant fragment exhibited resistance to phenamacril, and the transformed mutant with a copy of the sensitive fragment exhibited sensitivity to phenamacril. These results indicate that mutations in myosin-5 confers resistance to phenamacril in F. graminearum.

Application method affects pesticide efficiency and effectiveness in wheat fields

“…Fungicides containing phenamacril had the greatest effect, while 48% phenamacril · tebuconazole SC treatment (82.2%) was significantly more effective than phenamacril alone (66.7%). Phenamacril, a new fungicide classified as B6 (an phenylpyrrole fungicide selected from fludioxonil and fenpiclonil), has a new mode of action and is also considered environmentally safe, but its efficacy depends on the spray timing, concentration and method used . Studies of 48% phenamacril · tebuconazole SC application are therefore essential for enhancing its effectiveness.…”

The b‐ZIP transcription factor FgTfmI is required for the fungicide phenamacril tolerance and pathogenecity in Fusarium graminearum

“…In our previous study, we found that a point mutation S217 L or E420K in FgMyo1 is responsible for F. graminearum resistance to phenamacril . In addition, another 11 amino acid substitutions also confer resistance to phenamacril . Upregulation of drug target genes is another way to acquire resistance or tolerance to antifungal agents.…”

“…These include point mutation of FgMyo1 and up‐regulated FgMYO1 expression by FgTfmI. Mutations in the FgMyo1 resulted in high resistance to phenamacril, and were obtain with a high frequency in the laboratory screening with a high concentration of phenamacril . However, the deletion mutant ΔFgTfmI showed hypersensitivity to phenamacril (Fig.…”

“… Since 2007, it has been widely used in China for controlling FHB and rice bakanae disease caused by F. fujikuroi . Previous studies revealed that the class I myosin, FgMyoI is the drug target of phenamacril in F. graminearum . Phenamacril directly binds with FgMyo1 and suppresses the ATPase activity of FgMyo1 .…”

Baseline sensitivity of Fusarium graminearum from wheat fields in Henan, China, to metconazole and analysis of cross resistance with carbendazim and phenamacril

“…Benzimidazole fungicides bind to β‐tubulin to inhibit mycelial growth of plant pathogenic fungi, and the resistance mechanism is the point mutation of amino acids encoding the β‐tubulin in Botrytis cinerea and Sclerotinia sclerotiorum (Liu et al, , ; Zhu, Zhou, Li, Zhu, & Ma, ), or amino acids encoding the β 2 ‐tubulin gene in F. graminearum (Liu, Duan, Ge, Chen, & Zhou, ; Liu et al, ). The active target of the cyanoacrylate fungicide phenamacril is myosin 5 of the FGSC, and the point mutation in its coding gene leads to resistance of the FGSC to phenamacril (Hou et al, ; Li et al, ; Zheng et al, ). Therefore, there was no cross‐resistance between metconazole and carbendazim or phenamacril in F. graminearum , and positive cross‐resistance relationship between metconazole and epoxiconazole, difenoconazole or tebuconazole in F. graminearum .…”