Figure 1. The marneral and thalianol gene clusters in A. thaliana. (A) The present day thalianol and marneral clusters (bottom) and a proposed scheme for their formation based on the assumption that the two clusters were founded by duplication of an ancestral OSC/CYP705 gene pair. (B) Structures of thalianol, synthesized by THAS in the first committed step of the thalianol pathway; and marneral, synthesized by MRN1 in the first committed step of the marneral pathway. Figure adapted from reference 1.