title: EST mining identifies proteins putatively secreted by the anthracnose pathogen Colletotrichum truncatum.
abstract: BACKGROUND
  Colletotrichum truncatum is a haploid, hemibiotrophic, ascomycete fungal pathogen that causes anthracnose disease on many economically important leguminous crops. This pathogen exploits sequential biotrophic- and necrotrophic- infection strategies to colonize the host. Transition from biotrophy to a destructive necrotrophic phase called the biotrophy-necrotrophy switch is critical in symptom development. C. truncatum likely secretes an arsenal of proteins that are implicated in maintaining a compatible interaction with its host. Some of them might be transition specific.
  
  
  RESULTS
  A directional cDNA library was constructed from mRNA isolated from infected Lens culinaris leaflet tissues displaying the biotrophy-necrotrophy switch of C. truncatum and 5000 expressed sequence tags (ESTs) with an average read of > 600 bp from the 5-prime end were generated. Nearly 39% of the ESTs were predicted to encode proteins of fungal origin and among these, 162 ESTs were predicted to contain N-terminal signal peptides (SPs) in their deduced open reading frames (ORFs). The 162 sequences could be assembled into 122 tentative unigenes comprising 32 contigs and 90 singletons. Sequence analyses of unigenes revealed four potential groups: hydrolases, cell envelope associated proteins (CEAPs), candidate effectors and other proteins. Eleven candidate effector genes were identified based on features common to characterized fungal effectors, i.e. they encode small, soluble (lack of transmembrane domain), cysteine-rich proteins with a putative SP. For a selected subset of CEAPs and candidate effectors, semiquantitative RT-PCR showed that these transcripts were either expressed constitutively in both in vitro and in planta or induced during plant infection. Using potato virus X (PVX) based transient expression assays, we showed that one of the candidate effectors, i. e. contig 8 that encodes a cerato-platanin (CP) domain containing protein, unlike CP proteins from other fungal pathogens was unable to elicit a hypersensitive response (HR).
  
  
  CONCLUSIONS
  The current study catalogues proteins putatively secreted at the in planta biotrophy-necrotrophy transition of C. truncatum. Some of these proteins may have a role in establishing compatible interaction with the host plant.
authors.affiliation: Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2 Canada.
authors.forename: Vijai
authors.initials: V
authors.lastname: Bhadauria
authors.forename: Sabine
authors.initials: S
authors.lastname: Banniza
authors.forename: Albert
authors.initials: A
authors.lastname: Vandenberg
authors.forename: Gopalan
authors.initials: G
authors.lastname: Selvaraj
authors.forename: Yangdou
authors.initials: Y
authors.lastname: Wei
mesh_terms: D000595:Amino Acid Sequence; D020231:Colletotrichum / Q000235:genetics / Q000378:metabolism*; D004798:Enzymes / Q000235:genetics / Q000378:metabolism; D020224:Expressed Sequence Tags; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D027806:Lens Plant / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D018515:Plant Leaves / Q000382:microbiology; D021382:Protein Sorting Signals / Q000235:genetics; D016415:Sequence Alignment; D013997:Time Factors
chemical_list: D004798:Enzymes; D005656:Fungal Proteins; D008565:Membrane Proteins; D021382:Protein Sorting Signals