title: Comparative transcriptomics reveals different strategies of Trichoderma mycoparasitism.
abstract: BACKGROUND
  Trichoderma is a genus of mycotrophic filamentous fungi (teleomorph Hypocrea) which possess a bright variety of biotrophic and saprotrophic lifestyles. The ability to parasitize and/or kill other fungi (mycoparasitism) is used in plant protection against soil-borne fungal diseases (biological control, or biocontrol). To investigate mechanisms of mycoparasitism, we compared the transcriptional responses of cosmopolitan opportunistic species and powerful biocontrol agents Trichoderma atroviride and T. virens with tropical ecologically restricted species T. reesei during confrontations with a plant pathogenic fungus Rhizoctonia solani.
  
  
  RESULTS
  The three Trichoderma spp. exhibited a strikingly different transcriptomic response already before physical contact with alien hyphae. T. atroviride expressed an array of genes involved in production of secondary metabolites, GH16 ß-glucanases, various proteases and small secreted cysteine rich proteins. T. virens, on the other hand, expressed mainly the genes for biosynthesis of gliotoxin, respective precursors and also glutathione, which is necessary for gliotoxin biosynthesis. In contrast, T. reesei increased the expression of genes encoding cellulases and hemicellulases, and of the genes involved in solute transport. The majority of differentially regulated genes were orthologues present in all three species or both in T. atroviride and T. virens, indicating that the regulation of expression of these genes is different in the three Trichoderma spp. The genes expressed in all three fungi exhibited a nonrandom genomic distribution, indicating a possibility for their regulation via chromatin modification.
  
  
  CONCLUSIONS
  This genome-wide expression study demonstrates that the initial Trichoderma mycotrophy has differentiated into several alternative ecological strategies ranging from parasitism to predation and saprotrophy. It provides first insights into the mechanisms of interactions between Trichoderma and other fungi that may be exploited for further development of biofungicides.
authors: Research Area Biotechnology and Microbiology, Institute of Chemical Engineering, Vienna University of Technology, Gumpendorferstrasse 1a, A-1060, Vienna, Austria.
authors: Lea
authors: L
authors: Atanasova
authors: Stephane
authors: S
authors: Le Crom
authors: Sabine
authors: S
authors: Gruber
authors: Fanny
authors: F
authors: Coulpier
authors: Verena
authors: V
authors: Seidl-Seiboth
authors: Christian P
authors: CP
authors: Kubicek
authors: Irina S
authors: IS
authors: Druzhinina
mesh_terms: D015536:Down-Regulation; D020869:Gene Expression Profiling; D005800:Genes, Fungal / Q000235:genetics; D056265:Microbial Interactions / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D012232:Rhizoctonia / Q000502:physiology; D014242:Trichoderma / Q000235:genetics* / Q000502:physiology*; D015854:Up-Regulation