Succinate dehydrogenase inhibitor (SDHI) fungicide resistance prevention strategy

Abstract

Succinate dehydrogenase inhibitor (SDHI) fungicides are currently represented in New Zealand by eight active ingredients bixafen boscalid carboxin fluaxapyroxad fluopyram isopyrazam penthiopyrad and sedaxane They are either currently registered or undergoing development in New Zealand for use against a range of ascomycete and basiodiomycete pathogens in crops including cereals ryegrass seed apples pears grapes stonefruit cucurbits and kiwifruit These fungicides are considered to have medium to high risk of resistance development and resistance management is recommended by the Fungicide Resistance Action Committee (FRAC) in Europe Guidelines are presented for use of SDHI fungicides in New Zealand to help avoid or delay the development of resistance in the fungal pathogens that they target

Antifungal Agents in Agriculture: Friends and Foes of Public Health

“…Inhibition of fungal respiration by binding to the ubiquinone-binding site in the complex II of mitochondria [58] Carboxin, benodanil, flutolanil, fenfuran, fluxapryroxad, fluxypyram, thifluzamide, furametpyr [59] Botrytis cinerea, Alternaria alternate, Didymella brioniae, Podosphaeera xanthii, Corynespora cassiicola [60][61][62][63] Mutations in succinate dehydrogenase gene (amino acid substitution H257L or H257Y) [58,62] Anilinopyrimidine Inhibition of methionine synthesis and secretion of hydrolytic enzymes [64] Cyprodinil, mepanipyrim and pyrimethanil [65] Botrytis cinerea, Venturia inaequalis, Oculimacula spp. [66][67][68] This mechanism is not completely clear; it has been suggested to involve the overproduction of ABC (ATP-binding cassette) transporters or the modification of the target sites [69] Qo inhibitor Blocks fungal energy production through inhibition of mitochondrial respiration by binding to the Qo site of complex III [70] Azoxystrobin, mandestrobin, pyraclostrobin, kresoxim-methyl, dimoxystrobin, famoxadone, fluoxastrobin, fenamidone, pyribencarb [65] Erysiphe necator, Pseudopernospora cubensis, Venturia inaequalis, Alternaria solani, Pyrenophora teres, Pythium aphanidermatum, Pyrenophora tritici-repentis [65] Point mutations in the mitochondrial cytochrome b (cyt b) gene (G143A, F129L, G137R) [57,70] Morpholine Inhibition of ergosterol synthesis by blocking ∆14-reductase and ∆8-∆7-isomerase [6] Aldomorph, fenpropimorph, dodemorph, tridemorph [65] Decreased sensitivity in powdery mildews [16] Unknown [16] Azole Suppression of ergosterol synthesis by inhibiting 14α-demethylase [12] Imazalil, oxpoconazole, triflumizole, diniconazole, epoxiconazole, flutriafol [65] Zymoseptoria tritici, Venturia inaequalis, Penicillium digitatum, Cercospora beticola, Monilinia fructicola, Brumeriela jaapii, Botrytis cinérea, Penicillium digitatum, Zymoseptoria tritici [71,72] Mutations in cyp51, upregulation of cyp51 and the genes encoding membrane transporters [72] 2.2.1.…”

“…It was introduced into the market in 1966 [59] and targets basidiomycete pathogens [21]. Generation II SDHIs, including boscalid, fluxapryroxad, and fluxypyram, exhibit high antifungal activity in cereals, fruit trees, vegetables, and field crops [62]. This class of antifungals inhibits fungal respiration by blocking the ubiquinone-binding site (Q-site) in complex II of mitochondria [61].…”

“…Since this class of fungicides includes single-site inhibitors, the FRAC (Fungicide Resistance Action Committee) classified them as posing medium-high risk for emergence of resistant strains [65]. Interestingly, there are reports of an association between carboxin and boscalid resistance and mutations in the succinate dehydrogenase gene [62]. The most common mutations involved are the substitutions H257L and H257Y, which replace the histidine residue at position 257 (a ubiquinone-binding site) of the succinate dehydrogenase gene with leucine and tyrosine, respectively [58,62].…”

“…Interestingly, there are reports of an association between carboxin and boscalid resistance and mutations in the succinate dehydrogenase gene [62]. The most common mutations involved are the substitutions H257L and H257Y, which replace the histidine residue at position 257 (a ubiquinone-binding site) of the succinate dehydrogenase gene with leucine and tyrosine, respectively [58,62]. Botrytis cinerea, Alternaria alternate, Didymella brioniae, Podosphaeera xanthii, and Corynespora cassiicola are examples of fungi that have been reported to be resistant to SHDI [62].…”

Current possibilities and prospects of using fungicides in forestry

“…In accordance with the recommendations of FRAC, due to the presence of cross-resistance within the SDHI group, the preparations should be used prophylactically if the risk of the disease is high. They should not be used in emergency, particularly when the pathogen population is large (McKay et al 2011). These preparations should be used up to 2 times during the growing season best in combination with another active ingredient, or alternatively with substances from other groups that do not exhibit cross-resistance (McKay et al 2011).…”