Phytochemical Diversity of the Essential Oils of Mexican Oregano (Lippia graveolens Kunth) Populations along an Edapho‐Climatic Gradient

) Unidad de Biotecnologa, Centro de Investigacio´n Cientfica de Yucata´n, A. C. Calle 43 #130Chuburna´ de Hidalgo, Me´rida, Yucata´n 97200, Me´xicoMexican oregano (Lippia graveolens) is an important aromatic plant, mainly used as flavoring andusually harvested from non-cultivated populations. Mexican oregano essential oil showed importantvariation in the essential-oil yield and composition. The composition of the essential oils extracted byhydrodistillation from 14 wild populations of L. graveolens growing along an edaphoclimatic gradientwasevaluated.CharacterizationoftheoilsbyGC-FIDandGC/MSanalysesallowedtheidentificationof70 components, which accounted for 89–99% of the total oil composition. Principal component andhierarchical cluster analyses divided the essential oils into three distinct groups with contrasting oilcompositions, viz., two phenolic chemotypes, with either carvacrol (C) or thymol (T) as dominantcompounds(contents >75%ofthetotaloilcomposition),andanon-phenolicchemotype(S)dominatedby oxygenated sesquiterpenes. While Chemotype C was associated with semi-arid climate and shallowerand rockier soils, Chemotype T was found for plants growing under less arid conditions and in deepersoils. The plants showing Chemotype S were more abundant in subhumid climate. High-oil-yieldindividuals (>3%) were identified, which additionally presented high percentages of either carvacrol orthymol; these individuals are of interest, as they could be used as parental material for scientific andcommercial breeding programs.