title: The yeast signal sequence trap identifies secreted proteins of the hemibiotrophic corn pathogen Colletotrichum graminicola.
abstract: The hemibiotroph Colletotrichum graminicola is the causal agent of stem rot and leaf anthracnose on Zea mays. Following penetration of epidermal cells, the fungus enters a short biotrophic phase, followed by a destructive necrotrophic phase of pathogenesis. During both phases, secreted fungal proteins are supposed to determine progress and success of the infection. To identify genes encoding such proteins, we constructed a yeast signal sequence trap (YSST) cDNA-library from RNA extracted from mycelium grown in vitro on corn cell walls and leaf extract. Of the 103 identified unigenes, 50 showed significant similarities to genes with a reported function, 25 sequences were similar to genes without a known function, and 28 sequences showed no similarity to entries in the databases. Macroarray hybridization and quantitative reverse-transcriptase polymerase chain reaction confirmed that most genes identified by the YSST screen are expressed in planta. Other than some genes that were constantly expressed, a larger set showed peaks of transcript abundances at specific phases of pathogenesis. Another set exhibited biphasic expression with peaks at the biotrophic and necrotrophic phase. Transcript analyses of in vitro-grown cultures revealed that several of the genes identified by the YSST screen were induced by the addition of corn leaf components, indicating that host-derived factors may have mimicked the host milieu.
authors.affiliation: Institut fur Agrar-und Ernahrungswissenschaften, Martin-Luther-Universitat Halle-Wittenberg, Halle, Germany.
authors.forename: Jorrit-Jan
authors.initials: JJ
authors.lastname: Krijger
authors.forename: Ralf
authors.initials: R
authors.lastname: Horbach
authors.forename: Michael
authors.initials: M
authors.lastname: Behr
authors.forename: Patrick
authors.initials: P
authors.lastname: Schweizer
authors.forename: Holger B
authors.initials: HB
authors.lastname: Deising
authors.forename: Stefan G R
authors.initials: SG
authors.lastname: Wirsel
mesh_terms: D020231:Colletotrichum / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015723:Gene Library; D020133:Reverse Transcriptase Polymerase Chain Reaction; D003313:Zea mays / Q000382:microbiology*
chemical_list: D005656:Fungal Proteins