Comparative transcriptome analysis provides insights into the resistance regulation mechanism and inhibitory effect of fungicide phenamacril in Fusarium asiaticum

Fusarium asiaticum is a destructive phytopathogenic fungus that causes Fusarium head blight of wheat (FHB), leading to serious yield and economic losses to cereal crops worldwide. Our previous studies indicated that target-site mutations (K216R/E, S217P/L, or E420K/G/D) of Type I myosin FaMyo5 conferred high resistance to phenamacril. Here, we first constructed a sensitive strain H1S and point mutation resistant strains HA, HC and H1R. Then we conducted comparative transcriptome analysis of these strains in F. asiaticum after 1 μg·mL-1 and 10 μg·mL-1 phenamacril treatment. Results indicated that 2135 genes were differentially expressed (DEGs) among the sensitive and resistant strains. Among them, the DEGs encoding ammonium transporter MEP1/MEP2, nitrate reductase, copper amine oxidase 1, 4-aminobutyrate aminotransferase, amino-acid permease inda1, succinate-semialdehyde dehydrogenase, 2, 3-dihydroxybenzoic acid decarboxylase, etc., were significantly up-regulated in all the phenamacril-resistant strains. Compared to the control group, a total of 1778 and 2097 DEGs were identified in these strains after 1 μg·mL-1 and 10 μg·mL-1 phenamacril treatment, respectively. These DEGs involved in 4-aminobutyrate aminotransferase, chitin synthase 1, multiprotein-bridging factor 1, transcriptional regulatory protein pro-1, amino-acid permease inda1, ATP-dependent RNA helicase DED, acetyl-coenzyme A synthetase, sarcoplasmic/endoplasmic reticulum calcium ATPase 2, etc., showed significantly down-regulated expression in phenamacril-sensitive strain but not in resistant strains after phenamacril treatment. In addition, cyanide hydratase, mating-type protein MAT-1, putative purine nucleoside permease, plasma membrane protein yro2, etc., showed significantly co-down-regulated expression in all the strains after phenamacril treatment. Taken together, This study provide deep insights into the resistance regulation mechanism and inhibitory effect of fungicide phenamacril and these new annotated proteins or enzymes are worth for the discovery of new fungicide targets. Author summary Fungicide phenamacril resistance occur in F. asiaticum and the resistance regulation mechanis are systematic and complex. Here, we conducted comparative transcriptome analysis of a sensitive strain H1S and point mutation resistant strains HA, HC and H1R in F. asiaticum after 1 μg·mL-1 and 10 μg·mL-1 phenamacril treatment. Among these annotated proteins or enzymes, amino-acid permease inda1, 1, 4-aminobutyrate aminotransferase, chitin synthase 1, multiprotein-bridging factor 1, ATP-dependent RNA helicase DED, acetyl-coenzyme A synthetase, sarcoplasmic/endoplasmic reticulum calcium ATPase 2, cyanide hydratase, mating-type protein MAT-1, putative purine nucleoside permease, plasma membrane protein yro2, etc., were involved in the resistance regulation mechanism and inhibitory effect of fungicide phenamacril. Our paper provides a reference basis for the study of drug resistance in other microorganisms. In addition, the relevant proteins or enzymes annotated in our study also have reference value for the discovery of new fungicide targets.