title: The Sclerotinia sclerotiorum Slt2 mitogen-activated protein kinase ortholog, SMK3, is required for infection initiation but not lesion expansion.
abstract: Mitogen-activated protein kinases (MAPKs) play a central role in transferring signals and regulating gene expression in response to extracellular stimuli. An ortholog of the Saccharomyces cerevisiae cell wall integrity MAPK was identified in the phytopathogenic fungus Sclerotinia sclerotiorum. Disruption of the S. sclerotiorum Smk3 gene severely reduced virulence on intact host plant leaves but not on leaves stripped of cuticle wax. This was attributed to alterations in hyphal apical dominance leading to the inability to aggregate and form infection cushions. The mutation also caused loss of the ability to produce sclerotia, increased aerial hyphae formation, and altered hyphal hydrophobicity and cell wall integrity. Mutants had slower radial expansion rates on solid media but more tolerance to elevated temperatures. Loss of the SMK3 cell wall integrity MAPK appears to have impaired the ability of S. sclerotiorum to sense its surrounding environment, leading to misregulation of a variety of functions. Many of the phenotypes were similar to those observed in S. sclerotiorum adenylate cyclase and SMK1 MAPK mutants, suggesting that these signaling pathways co-regulate aspects of fungal growth, physiology, and pathogenicity.
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.|b Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
authors: Zafer Dallal
authors: ZD
authors: Bashi
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.
authors: Sanjaya
authors: S
authors: Gyawali
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.
authors: Diana
authors: D
authors: Bekkaoui
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.
authors: Cathy
authors: C
authors: Coutu
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.
authors: Leora
authors: L
authors: Lee
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.
authors: Jenny
authors: J
authors: Poon
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.
authors: S Roger
authors: SR
authors: Rimmer
authors: b Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
authors: George G
authors: GG
authors: Khachatourians
authors: a Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada.|b Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
authors: Dwayne D
authors: DD
authors: Hegedus
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics; D001203:Ascomycota / Q000201:enzymology* / Q000254:growth & development / Q000472:pathogenicity; D029688:Brassica napus / Q000382:microbiology; D002473:Cell Wall / Q000378:metabolism; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000502:physiology*; D015870:Gene Expression; D025301:Hyphae / Q000201:enzymology / Q000254:growth & development / Q000472:pathogenicity; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D025282:Mycelium / Q000201:enzymology / Q000254:growth & development / Q000472:pathogenicity; D010641:Phenotype; D010766:Phosphorylation; D010935:Plant Diseases / Q000382:microbiology*; D011499:Protein Processing, Post-Translational; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014774:Virulence / Q000235:genetics
chemical_list: C438144:ASI1 protein, S cerevisiae; D005656:Fungal Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D020928:Mitogen-Activated Protein Kinases; D000262:Adenylyl Cyclases
keywords: Sclerotinia sclerotiorum; cell wall integrity; infection; intégrité de la paroi cellulaire; mitogen activated protein kinase; protéine kinase activée par les mitogènes