title: The putative phospholipase Lip2 counteracts oxidative damage and influences the virulence of Ustilago maydis.
abstract: Ustilago maydis is an obligate biotrophic fungal pathogen which causes common smut disease of corn. To proliferate in host tissue, U. maydis must gain access to nutrients and overcome plant defence responses, such as the production of reactive oxygen species. The elucidation of the mechanisms by which U. maydis meets these challenges is critical for the development of strategies to combat smut disease. In this study, we focused on the contributions of phospholipases (PLs) to the pathogenesis of corn smut disease. We identified 11 genes encoding putative PLs and characterized the transcript levels for these genes in the fungus grown in culture and during infection of corn tissue. To assess the contributions of specific PLs, we focused on two genes, lip1 and lip2, which encode putative phospholipase A2(PLA2) enzymes with similarity to platelet-activating factor acetylhydrolases. PLA2enzymes are known to counteract oxidative damage to lipids in other organisms. Consistent with a role in the mitigation of oxidative damage, lip2 mutants were sensitive to oxidative stress provoked by hydrogen peroxide and by increased production of reactive oxygen species caused by inhibitors of mitochondrial functions. Importantly, mutants defective in lip2, but not lip1, were attenuated for virulence in corn seedlings. Finally, a comparative analysis of fatty acid and cardiolipin profiles in the wild-type strain and a lip2 mutant revealed differences consistent with a protective role for Lip2 in maintaining lipid homeostasis and mitochondrial health during proliferation in the hostile host environment.
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver V6T 1Z3, BC, Canada.|The Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Lambie
authors.affiliation: The Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: Matthias
authors.initials: M
authors.lastname: Kretschmer
authors.affiliation: The Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Croll
authors.affiliation: Department of Botany, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: Tegan M
authors.initials: TM
authors.lastname: Haslam
authors.affiliation: Department of Botany, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: Ljerka
authors.initials: L
authors.lastname: Kunst
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver V6T 1Z3, BC, Canada.|The Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: Jana
authors.initials: J
authors.lastname: Klose
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver V6T 1Z3, BC, Canada.|The Michael Smith Laboratories, University of British Columbia, Vancouver V6T 1Z4, BC, Canada.
authors.forename: James W
authors.initials: JW
authors.lastname: Kronstad
mesh_terms: D002308:Cardiolipins / Q000378:metabolism; D019069:Cell Respiration; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D016681:Genome, Fungal; D006238:Haploidy; D009154:Mutation / Q000235:genetics; D018384:Oxidative Stress; D010740:Phospholipases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014588:Ustilago / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
chemical_list: D002308:Cardiolipins; D005656:Fungal Proteins; D012333:RNA, Messenger; D010740:Phospholipases
keywords: corn; fungal pathogenesis; maize; mitochondria; smut disease