02602nas a2200253   4500008004100000245013900041210006900180260027100249300001400520490000700534520150200541653001502043653003002058653001402088653001802102653002702120653001702147100001902164700002202183700001402205700001802219700001402237856009702251       2003                        eng d00aQualitative and quantitative variation in monoterpene co-occurrence and composition in the essential oil of Thymus vulgaris chemotypes0 aQualitative and quantitative variation in monoterpene cooccurren  aAffiliation: Ctr. d'Ecologie Fonct. et Evolutive, CNRS, 1919 Route de Mende, 34293 Montpellier Cedex 5, France; Affiliation: Lab. Chim. des Huiles Essentielles, Universite Blaise Pascal de Clermont, Campus des Cézeaux, 24 Avenue des Landais, 63177 Aubiec2003/04//  a859 - 8800 v293 aThymus vulgaris has a chemical polymorphism with six different chemotypes that show marked spatial segregation in nature. Although some populations have a single chemotype in majority, many have two or three chemotypes. In this study we analyze the quantitative variation among T. vulgaris populations in the percentage of oil composed of the dominant monoterpene(s) for each chemotype. In general, phenolic chemotypes (thymol and carvacrol), which occur at the end of the biosynthetic chain, have a significantly lower proportion of their oil composed of their dominant monoterpene than nonphenolic chemotypes (geraniol, α-terpineol, and linalool). This is due to the presence of high amounts of precursors (γ-terpinene and paracymene) in the oil of phenolic chemotypes. The essential oil of the nonphenolic thuyanol chemotype has four characteristic monoterpenes that together make up a lower proportion of the oil than the single dominant monoterpene of the other nonphenolic chemotypes. For all chemotypes, the percentage composition of the dominant monoterpene decreased significantly at sites where the chemotype is not the majority type. This decrease is correlated with a significant increase in either the proportion of the two precursors for the thymol chemotype or the monoterpenes characteristic of the other chemotypes at the site. The latter result suggests that a plant with dominant genes is responsible for the production of different monoterpenes can produce several molecules.10aAdaptation10aEssential oil composition10aLamiaceae10aMediterranean10aMonoterpene production10aPolymorphism1 aThompson, J, D1 aChalchat, J, C -C1 aMichet, A1 aLinhart, Y, B1 aEhlers, B  uhttp://www.scopus.com/scopus/inward/record.url?eid=2-s2.0-0242499958&partnerID=40&rel=R6.5.0