Exploring the mechanism of resistance of Rhizoctonia cerealis to trifloxystrobin

Wheat sheath eyespot (WES) is an important disease in wheat production. Due to the lack of wheat varieties with stable resistance and high yield, chemical agents are currently the main control method. Trifloxystrobin has good control effects on a variety of plant pathogenic fungi due to its wide fungicidal spectrum and high fungicidal activity. Laboratory preliminary studies have shown that trifloxystrobin has good antibacterial activity against Rhizoctonia cerealis , but is there a risk of drug resistance after long-term application? And what is the mechanism by which R. cerealis develops resistance to it? Both need further study. In this study, the trifloxystrobin-resistant R. cerealis obtained by drug domestication in the early stage of the laboratory was used as the main research material to study the biological characteristics and R. cerealis resistance mechanism to trifloxystrobin. Our results showed that compared with the sensitive isolates, the mycelial growth rate of the trifloxystrobin-resistant R. cerealis mutant was reduced, the ability to produce sclerotia was enhanced, the pathogenicity to the host wheat was enhanced, and it was more sensitive to temperature. At the same time, the results of osmotic pressure measurement showed that compared with the sensitive strain, the mycelial growth rate of the trifloxystrobin-resistant R. cerealis mutant under different pH and salt stresses had no significant difference, while low concentration (< 20 g/L) of glucose stress promoted the mycelial growth of the trifloxystrobin-resistant R. cerealis mutants to a certain extent. In addition, there was no cross-resistance between trifloxystrobin-resistant R. cerealis and the commonly used fungicides difenoconazole, flufenoxazole, flutriafol, tebuconazole, metconazole and carbendazim, and there was negative cross-resistance between it and propiconazole, hexaconazole, thiofuran and fluazinam, that is, the above fungicides can be used as alternative fungicides in areas where wheat sheath blight is resistant to trifloxystrobin. The research results provide data support for clarifying the resistance mechanism of R. cerealis to trifloxystrobin, which is of great significance for effectively preventing and controlling wheat sheath blight and ensuring the safe production of wheat.