title: Physical-chemical plant-derived signals induce differentiation in Ustilago maydis.
abstract: Ustilago maydis is able to initiate pathogenic development after fusion of two haploid cells with different mating type. On the maize leaf surface, the resulting dikaryon switches to filamentous growth, differentiates appressoria and penetrates the host. Here, we report on the plant signals required for filament formation and appressorium development in U. maydis. In vitro, hydroxy-fatty acids stimulate filament formation via the induction of pheromone genes and this signal can be bypassed by genetically activating the downstream MAP kinase module. Hydrophobicity also induces filaments and these resemble the dikaryotic filaments formed on the plant surface. With the help of a marker gene that is specifically expressed in the tip cell of those hyphae that have formed an appressorium, hydrophobicity is shown to be essential for appressorium development in vitro. Hydroxy-fatty acids or a cutin monomer mixture isolated from maize leaves have a stimulatory role when a hydrophobic surface is provided. Our results suggest that the early phase of communication between U. maydis and its host plant is governed by two different stimuli.
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Department of Organismic Interactions, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
authors.forename: Artemio
authors.initials: A
authors.lastname: Mendoza-Mendoza
authors.forename: Patrick
authors.initials: P
authors.lastname: Berndt
authors.forename: Armin
authors.initials: A
authors.lastname: Djamei
authors.forename: Carolin
authors.initials: C
authors.lastname: Weise
authors.forename: Uwe
authors.initials: U
authors.lastname: Linne
authors.forename: Mohamed
authors.initials: M
authors.lastname: Marahiel
authors.forename: Miroslav
authors.initials: M
authors.lastname: Vranes
authors.forename: Jörg
authors.initials: J
authors.lastname: Kämper
authors.forename: Regine
authors.initials: R
authors.lastname: Kahmann
mesh_terms: D005227:Fatty Acids / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal; D057927:Hydrophobic and Hydrophilic Interactions; D025301:Hyphae / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D020935:MAP Kinase Signaling System / Q000235:genetics; D008563:Membrane Lipids / Q000378:metabolism; D010675:Pheromones / Q000235:genetics; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D011401:Promoter Regions, Genetic; D012331:RNA, Fungal / Q000235:genetics; D015398:Signal Transduction; D014588:Ustilago / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity; D003313:Zea mays / Q000378:metabolism / Q000382:microbiology*
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D010675:Pheromones; D012331:RNA, Fungal; C000521:cutin