Study on Mechanisms of Resistance to SDHI Fungicide Pydiflumetofen in Fusarium fujikuroi

Abstract

Rice bakaenii disease (RBD) is a widespread and devastating disease mainly caused by Fusarium fujikuroi. Pydiflumetofen (Pyd) is a novel succinate dehydrogenase inhibitor (SDHI) with strong inhibitory activity against F. fujikuroi, but the mechanism of resistance to Pyd has not been well studied for this pathogen. Through fungicide adaption, a total of 12 Pyd-resistant mutants were obtained and the resistance level could be divided into three categories of high resistance (HR), moderate resistance (MR), and low resistance (LR) with resistance factors (RF) of 184.04–672.90, 12.63–42.49, and <10, respectively. Seven genotypes of point mutations in FfSdh genes (FfSdhBH248L, FfSdhBH248D, FfSdhBH248Y, FfSdhC2 A83V, FfSdhC2 H144Y, FfSdhDS106F, and FfSdhDE166K) were found in these mutants, among which genotype FfSdhBH248L and FfSdhC2 A83V mutants showed HR, genotype FfSdhBH248D, FfSdhBH248Y, FfSdhC2 H144Y, and FfSdhDE166K mutants showed MR, and genotype FfSdhDS106F mutants showed LR. Moreover, all the substitutions of amino acid point mutations including FfSdhBH248L/D/Y, FfSdhC2 A83V,H144Y, and FfSdhDS106F,E166K conferring resistance to Pyd in F. fujikuroi were verified by protoplast transformation. Additionally, a positive cross-resistance was detected between Pyd and another SDHI fungicide penflufen, while no cross-resistance was detected between Pyd and phenamacril, prochloraz, azoxystrobin, carbendazim, or fludioxonil. Although pathogenicity of the mutants was increased compared with that of the wild-type parental strains, the mycelial growth rate and spore production levels of the resistant mutants were significantly decreased (P < 0.05), indicating significant fitness cost of resistance to Pyd in F. fujikuroi. Taken together, the risk of resistance to Pyd in F. fujikuroi might be moderate, and appropriate precautions against resistance development in natural populations should be taken into account when Pyd is used for the control of RBD.

Functional Differentiation of the Succinate Dehydrogenase Subunit SdhC Governs the Sensitivity to SDHI Fungicides, ROS Homeostasis, and Pathogenicity in Fusarium asiaticum

“…To date, pydiflumetofen (PYD), a novel succinate dehydrogenase inhibitor, is the only SDHI fungicide registered for controlling wheat FHB with excellent efficacy in the field. , However, the PYD resistance was reported in another phytopathogenic fungi, including F. graminearum, Fusarium pseudograminearum, Fusarium fujikuroi, Botrytis cinerea, Magnaporthe oryzae, and Didymella bryoniae. − Our previous study showed that SdhB H248Y , SdhC 1 A64V , or SdhC 1 R67K mutations are responsible for the resistance to PYD in F. asiaticum .…”

Design of a delivery vehicle chitosan-based self-assembling: controlled release, high hydrophobicity, and safe treatment of plant fungal diseases

“…Those played an instrumental role in dealing with the demand for food as a result of rapid population growth [ 10 – 14 ]. Nevertheless, owing to the excessive use of fungicides with the same or similar mode of action, fungicide resistance is rapidly increasing, which resulting in the decrease of ability to control fungal diseases in crops [ 15 – 17 ]. Meanwhile, non-target and environmental hazards have emerged along with fungicide utilization [ 18 , 19 ].…”