Flutolanil and carboxin resistance in Coprinus cinereus conferred by a mutation in the cytochrome b 560 subunit of succinate dehydrogenase complex (Complex II)

Abstract

A gene that confers resistance to the systemic fungicide flutolanil was isolated from a mutant strain of the basidiomycete Coprinus cinereus. The flutolanil resistance gene was mapped to a chromosome of approximately 3.2 Mb, and a chromosome-specific cosmid library was constructed. Two cosmid clones that were able to transform a wild-type, flutolanil-sensitive, strain of C. cinereus to resistance were isolated from the library. Analysis of a subclone containing the resistance gene revealed the presence of the sdhC gene, which encodes the cytochrome b560 subunit of the succinate dehydrogenase (SDH) complex (Complex II) in the mitochondrial membrane. Comparison between the sdhC gene of a wild-type strain and that of a mutant strain revealed a single point mutation, which results in the replacement of Asn by Lys at position 80. Measurements of succinate-cytochrome c reductase activity in the transformants with mutant sdhC gene(s) suggest that flutolanil resistance of the fungus is caused by a decrease in the affinity of the SDH complex for flutolanil. This sdhC mutation also conferred cross-resistance against another systemic fungicide, carboxin, an anilide that is structurally related to flutolanil. In other organisms carboxin resistance mutations have been found in the genes sdhB and sdhD, but this is the first demonstration that a mutation in sdhC can also confer resistance. The mutant gene cloned in this work can be utilized as a dominant selectable marker in gene manipulation experiments in C. cinereus.

Exploring Mechanisms of Resistance to Respiratory Inhibitors in Field Strains of Botrytis cinerea , the Causal Agent of Gray Mold

“…2) (35, 59). Mutations in sdhC were previously found in several laboratory and field mutants (29,39,62). Moreover, a recent report indicated that the H134R mutation is prevalent in SdhC of A. alternata collected from pistachios (65).…”

Effectiveness of control strategies againstBotrytis cinereain vineyard and evaluation of the residual fungicide concentrations

“…[9] The carboxamides block the energy production in the fungal cells, by inhibiting the succinate ubiquinone reductases containing sulphur. [10] In most grapevine growing areas, populations of B. cinerea resistant to benzimidazoles and/or dicarboximides are widespread, [11] but their incidence is decreasing, thanks to the introduction of anilinopyrimidines and phenylpyrroles that provide good levels of disease control. [12] The availability of novel classes of compounds does not imply the total replacement of the older fungicides, but represents a new powerful tool for the growers.…”

Detection of Fungicide Resistance

“…The primary target of the SDHI fungicides is the SDH complex that consists of four subunits: a flavoprotein (Fp) subunit (SdhA), an iron-sulfur protein (Ip) subunit (SdhB), and two membrane-anchored protein subunits (SdhC and SdhD). Mutations conferring resistance have been found in the SDHB (Avenot et al 2008) and SDHC (Ito et al 2004) and SDHD subunits (Avenot et al 2009). …”