Detection of SdhC-I87F in cereal leaf rusts

We detected isolates with SdhC-I87F-conferring mutations that were slightly SDHI-adapted in the barley leaf rust Puccinia hordei in France and the UK in 2019. SdhC-I87F of P. hordei is orthologous to SdhC-I86F in Phakopsora pachyrhizi , and SdhC-I88F in Puccinia horiana induced SDHI resistance. Nevertheless, the field performance of SDHIs against P. hordei was good, although strains with SdhC-I87F dominated the field. The sensitivity ranges were narrow for wheat leaf rust and Puccinia triticina in 2019; however, isolates with slightly higher EC 50 values were obtained in southern France and the eastern UK in 2021. These isolates of P. triticina harbored an orthologous SdhC-I87F-conferring mutation. The range of EC 50 values for the SDHI fungicide inpyrfluxam overlapped between the wild type and SdhC-I87F isolates. Further analyses are currently underway.