Horizontal gene transfer
It is well known that many organisms across all domains produce secondary metabolites. Fungi are known to be prolific in this regard. Product mining was well underway in the 1990s for the genus "Podospora". Specifically for "Podospora anserina", two new natural products classified as pentaketides, specifically derivatives of benzoquinones, were discovered; these showed antifungal, antibacterial, and cytotoxic activities. Horizontal gene transfer is common in bacteria and between prokaryotes and eukaryotes yet is more rare between eukaryotic organisms. Between fungi, secondary metabolite clusters are good candidates for HGT. For example, a functional "ST" gene cluster that produces sterigmatocystin was found in "Podospora anserina" and originally derived from "Aspergillus". This cluster is well-conserved, notably the transcription-factor binding sites. Sterigmatocystin itself is toxic and is a precursor to another toxic metabolite, aflatoxin.