The Succinate Dehydrogenase Inhibitor Fungicides: Fungal Resistance and its Management

Effective disease management is essential to mitigate the rapid emergence of resistant pathogen
populations. An important group of fungicides that play a pivotal role in the integrated management systems,
among others, also because of their low environmental toxicity, are succinate dehydrogenase inhibitors, which
act by binding to the mitochondrial complex II of the respiratory system. Unlike first-generation SDHIs (e.g.,
carboxin and oxycarboxin), which exhibit high efficacy against basidiomycetes, newer compounds in this class
(e.g., cyclobutrifluram, furametpyr, and inpyrfluxam) demonstrate broad-spectrum activity against a wide range
of fungal species. However, their repeated and inadequate application strategies, can exert strong selection
pressure, favoring the development of resistant fungal genotypes, which may ultimately compromise fungicide
efficacy. This review examines both historical and recent advancements in understanding the molecular
mechanisms underlying SDHI resistance, as well as other factors influencing the evolution of resistance. In
addition, it provides an insight into strategies for the effective use of newly developed SDHI molecules and
highlights key research directions for combating resistance in the future.