Towards identification of the genetic basis of 6-pentyl-alphapyrone biosynthesis in Trichoderma atroviride
Student/in: Alexander Eschlböck, BSc
Termin: 09.11.2023, 12:30 Uhr
Ort: Seminarraum Biologie, Foyer
1. Prüfer/in: Univ.-Prof. Mag. Dr. Susanne Zeilinger-Migsich
2. Prüfer/in: ao. Univ.-Prof. Mag. Dr. Ursula Peintner
Vorsitzende/r: Priv.-Doz. Mag. Dr. Andreas Wagner
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Abstract
The filamentous fungus Trichoderma atroviride is commonly used as a biocontrol agent against crop diseases caused by other fungi due to its high antagonistic activity that includes mycoparasitism and the production of antifungal and antibiotic secondary metabolites (SM). One of these bioactive and mycoparasitism associated SMs is 6-pentyl-𝛼-pyrone (6-PP). This volatile organic compound is produced by some Trichoderma species like Trichoderma atroviride and Trichoderma harzianum but not Trichoderma reseei or Trichoderma virens. It was previously shown that 6-PP production in T. atroviride is inhibited by white light and reaches its maximum when the fungus is cultivated in complete darkness. Although a recent study has evidenced a polyketide nature of 6-PP, its exact biosynthesis pathway has not yet been elucidated and the genes responsible for 6-PP production are still unknown. The aim of this study was to identify candidates with a putative role in 6-PP biosynthesis among the 22 PKS genes encoded in T. atroviride. Comparative analyses of PKS gene transcription in the T. atroviride wild type, cultivated in the presence of light or in complete darkness, as well as in mutants with altered 6-PP production resulted in the identification of the most promising candidates. This combination of transcriptomic and metabolomic analyses provided evidence that pks4 is involved in the biosynthesis of 6-PP. Moreover, quantification of 6-PP levels produced by histone deacetylase-deficient mutants missing the hda1 gene revealed a regulatory role of Hda1 on the genes responsible for 6-PP production. Finally, a deletion mutant lacking the most promising candidate gene for 6-PP production was generated, and transcriptomic profiling of PKSs and 6-PP measurement were performed.