Fig 12.

(A) Proposed ancestral TRI cluster based on the distribution of TRI genes among fungi examined in the current study. (B) Proposed ancestral trichothecene biosynthetic pathway based on inferred gene content of the ancestral TRI cluster and knowledge of TRI gene functions. (C) The presence of two acetyl/acyl transferase genes in the proposed ancestral cluster raises the possibility of a branch at the end of the ancestral pathway that would result in the formation of two trichothecene analogs: 4-acetyl EPT and 4-butenoyl EPT.