Genetic control of the oil content in Thymus vzdgaris L.: a case of polymorphism in a biosynthetic chain

Six distinct chemotypes of the mediterranean 7’lzymus vulgaris L. are characterized by differences in the major monoterpenes produced. The nature of the monoterpenes is shown to be controlled by a series of loci. Each locus probably has a dominant and a recessive allele. Epistatic relationships between these loci are interpreted by assuming that terpenes are end products of branches from the same biosynthetic pathway. The most dominant types, which correspond to the monoterpenes produced at the beginning of the chain, show the most important potential genetic diversity. There is good evidence that regulatory genes are involved in this system.