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In recent years, a new generation of succinate dehydrogenase inhibitors (SDHIs, mitochondrial complex Ⅱ inhibitors) such as boscalid and penthiopyrad was intensively developed.Other fungicides which possess the same mode of action have also been commercialized and at present twenty SDHI fungicides are known in total.The risk of resistance development to SDHI fungicides is regarded medium to high, and SDHI fungicide resistance has already been reported in many pathogen-crop combinations.However, the pattern of cross-resistance is unique among SDHI fungicides.The lack of cross-resistance to fluopyram was found in highly boscalid-resistant isolates of some fungi including Corynespora cassiicola, Podoshaera xanthii, Botrytis cinerea and others.This interesting phenomenon in boscalid-resistant isolates was correlated with the H 277 Y/R mutations of sdhB genes, encoding a subunit of fungicide-targeted succinate dehydrogenase, suggesting differential binding of individual fungicides to the target site of protein molecule.More recently, a novel SDHI fungicide benzovindiflupyr has been shown to be effective against Colletotrichum species, inherently insensitive (naturally resistant) to boscalid, fluxapyroxad, and fluopyram.The sdhB, sdhC and sdhD genes were partially sequenced, but, despite high polymorphisms, no apparent resistance mutations were found in Colletotrichum species.Other mechanism (s) than fungicide target-site modification might be responsible for differential sensitivity of Colletotrichum species to SDHI fungicides.In this paper, recent development of SDHI fungicides and the progress of research on resistance to this class of fungicides will be discussed.