title: A new point mutation in the iron-sulfur subunit of succinate dehydrogenase confers resistance to boscalid in Sclerotinia sclerotiorum.
abstract: Research has established that mutations in highly conserved amino acids of the succinate dehydrogenase (SDH) complex in various fungi confer SDH inhibitor (SDHI) resistance. For Sclerotinia sclerotiorum (Lib.) de Bary, a necrotrophic fungus with a broad host range and a worldwide distribution, boscalid resistance has been attributed to the mutation H132R in the highly conserved SdhD subunit protein of the SDH complex. In our previous study, however, only one point mutation, A11V in SdhB (GCA to GTA change in SdhB), was detected in S. sclerotiorum boscalid-resistant (BR) mutants. In the current study, replacement of the SdhB gene in a boscalid-sensitive (BS) S. sclerotiorum strain with the mutant SdhB gene conferred resistance. Compared with wild-type strains, BR and GSM (SdhB gene in the wild-type strain replaced by the mutant SdhB gene) mutants were more sensitive to osmotic stress, lacked the ability to produce sclerotia and exhibited lower expression of the pac1 gene. Importantly, the point mutation was not located in the highly conserved sequence of the iron-sulfur subunit of SDH. These results suggest that resistance based on non-conserved vs. conserved protein domains differs in mechanism. In addition to increasing our understanding of boscalid resistance in S. sclerotiorum, the new information will be useful for the development of alternative antifungal drugs.
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, National-Local Joint Engineering Research Center for Green Pesticide Invention and Application, Nanjing, 210095, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, National-Local Joint Engineering Research Center for Green Pesticide Invention and Application, Nanjing, 210095, China.
authors.forename: Yabing
authors.initials: Y
authors.lastname: Duan
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, National-Local Joint Engineering Research Center for Green Pesticide Invention and Application, Nanjing, 210095, China.
authors.forename: Jianxin
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, National-Local Joint Engineering Research Center for Green Pesticide Invention and Application, Nanjing, 210095, China.
authors.forename: Mingguo
authors.initials: M
authors.lastname: Zhou
mesh_terms: D001203:Ascomycota / Q000502:physiology*; D005658:Fungi / Q000472:pathogenicity*; D015870:Gene Expression; D007506:Iron-Sulfur Proteins / Q000235:genetics*; D010802:Phylogeny; D017354:Point Mutation; D013385:Succinate Dehydrogenase / Q000235:genetics*
chemical_list: D007506:Iron-Sulfur Proteins; D013385:Succinate Dehydrogenase
keywords: SDHI fungicides; Sclerotinia sclerotiorum; boscalid; fungicide resistance