Fusarium graminearumFgSdhC1 point mutation A78V confers resistance to the succinate dehydrogenase inhibitor pydiflumetofen

Abstract

BACKGROUND Fusarium head blight (FHB) caused by Fusarium graminearum complex (Fg) is a devastating disease of cereal crops worldwide. The succinate dehydrogenase inhibitor, pydiflumetofen, was registered for management of FHB in China in 2019. Previously, laboratory‐induced pydiflumetofen‐resistant (PyR) mutants of Fg have been characterized. However, resistance situation of Fg to pydiflumetofen in the field remains largely unknown. RESULTS After screening 6468 isolates of Fg from various regions of China, six PyR isolates were identified. All six resistant isolates exhibited no fitness penalties based on mycelial growth, conidiation and virulence. However, no cross‐resistance between pydiflumetofen and azoxystrobin, tebuconazole or fludioxonil in Fg was detected. Genome‐sequencing revealed that all six PyR isolates contained a point mutation A78V in FgSdhC1 (FgSdhC1A78V). Genetic replacement assay further confirmed that FgSdhC1A78V conferred resistance of Fg to pydiflumetofen. Based on this, a mismatch allele‐specific polymerase chain reaction was developed for rapidly detecting the PyR isolates containing the FgSdhC1A78V mutation in Fg. CONCLUSION This is the first time that resistance of Fg to pydiflumetofen in the field was reported and point mutation FgSdhC1A78V conferring resistance of Fg to pydiflumetofen was confirmed. This study provides critical information for monitoring and managing pydiflumetofen resistance in Fg.

Resistance Risk and Resistance-Related Point Mutation in SdhB and SdhC1 of Cyclobutrifluram in Fusarium pseudograminearum

“…Similar results have been reported in previous studies, namely, that F. graminearum isolates recovered in the field were spontaneously resistant to pydiflumetofen with 9×10 –4 resistance frequency . After the 10th subculture, the RF of mutants was still greater than 200, and this was attributed to a high resistance level though lower than that of the first generation.…”

“…Previous studies had already shown that several point mutations in the SDH proteins of Fusarium species could cause SDHIs resistance. Point mutation A78V in FgSdhC 1 confers resistance to pydiflumetofen in F. graminearum, 26 while point mutations R86C or T77I in FgSdhC 2 and A-to-T mutation at the −57 bp of the 5′ untranslated region (5′-UTR) of FgSdhC 1 confers resistance to flubeneteram. 16 Furthermore, FaSdhB H248Y , FaSdhC 1 A64V , or FaSdhC 1 R67K mutations are associated with the resistance of F. asiaticum to pydiflumetofen.…”

“…Similar results have been reported in previous studies, namely, that F. graminearum isolates recovered in the field were spontaneously resistant to pydiflumetofen with 9×10 −4 resistance frequency. 26 After the 10th subculture, the RF of mutants was still greater than 200, and this was attributed to a a EC 50 to cyclobutrifluram of transformants with or without point mutation was determined using a mycelial inhibition method. The inhibition ratio of some transformants grew on YBA plates containing 4 μg/mL cyclobutrifluram is less than 50 percent, meaning EC 50 of transformants to cyclobutrifluram is equal or greater than 4 μg/mL.…”

Multiple Mutations in SDHB and SDHC2 Subunits Confer Resistance to the Succinate Dehydrogenase Inhibitor Cyclobutrifluram in Fusarium fujikuroi

“…In Alternaria alternata, the mutations SdhB H277Y/R/L , SdhC H134R,S135R , and SdhD D123E,H133R/P/T were verified to confer resistance to boscalid. , The mutations FaSdhB H248Y and FaSdhC 1 A64V,R67K conferred resistance to pydiflumetofen in Fusarium asiaticum . The mutations FgSdhC 1 A78V and FgSdhC 2 A83V,R86C,R86H conferred resistance of Fusarium graminearum to pydiflumetofen, , and the mutations FgSdhC 2 T77I,R86C or −57 bp A to T mutation in the 5′ UTR of FgSdhC 1 conferred resistance of F. graminearum to flubeneteram .…”

“…38,39 The mutations FaSdhB H248Y and FaSdh-C 1 A64V,R67K conferred resistance to pydiflumetofen in Fusarium a s i a t i c u m . 3 1 T h e m u t a t i o n s F g S d h C 1 A 7 8 V a n d FgSdhC 2 A83V,R86C,R86H conferred resistance of Fusarium graminearum to pydiflumetofen, 40,41 and the mutations FgSdhC 2 T77I,R86C or −57 bp A to T mutation in the 5′ UTR of FgSdhC 1 conferred resistance of F. graminearum to flubeneteram. 42 FfSdhB H248L/Y and FfSdhC 2 A83V are conserved mutated positions in homologous proteins of other phytopathogenic microorganisms, 31,37−41 indicating that there is high relevance between these amino acid substitutions and SDHI resistance in different fungal species.…”