title: Phytochemical diversity of the essential oils of Mexican Oregano (Lippia graveolens Kunth) populations along an Edapho-climatic gradient.
abstract: Mexican oregano (Lippia graveolens) is an important aromatic plant, mainly used as flavoring and usually harvested from non-cultivated populations. Mexican oregano essential oil showed important variation in the essential-oil yield and composition. The composition of the essential oils extracted by hydrodistillation from 14 wild populations of L. graveolens growing along an edaphoclimatic gradient was evaluated. Characterization of the oils by GC-FID and GC/MS analyses allowed the identification of 70 components, which accounted for 89-99% of the total oil composition. Principal component and hierarchical cluster analyses divided the essential oils into three distinct groups with contrasting oil compositions, viz., two phenolic chemotypes, with either carvacrol (C) or thymol (T) as dominant compounds (contents >75% of the total oil composition), and a non-phenolic chemotype (S) dominated by oxygenated sesquiterpenes. While Chemotype C was associated with semi-arid climate and shallower and rockier soils, Chemotype T was found for plants growing under less arid conditions and in deeper soils. The plants showing Chemotype S were more abundant in subhumid climate. High-oil-yield individuals (>3%) were identified, which additionally presented high percentages of either carvacrol or thymol; these individuals are of interest, as they could be used as parental material for scientific and commercial breeding programs.
authors.affiliation: Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, A. C. Calle 43 #130 Chuburná de Hidalgo, Mérida, Yucatán 97200, México, (phone: +52-999-9428330; fax: +52-999-9813900). lumali@cicy.mx.
authors.forename: Luz María
authors.initials: LM
authors.lastname: Calvo-Irabién
authors.forename: Victor
authors.initials: V
authors.lastname: Parra-Tabla
authors.forename: Violeta
authors.initials: V
authors.lastname: Acosta-Arriola
authors.forename: Fabiola
authors.initials: F
authors.lastname: Escalante-Erosa
authors.forename: Luciana
authors.initials: L
authors.lastname: Díaz-Vera
authors.forename: Gabriel R
authors.initials: GR
authors.lastname: Dzib
authors.forename: Luis Manuel
authors.initials: LM
authors.lastname: Peña-Rodríguez
mesh_terms: D016000:Cluster Analysis; D008401:Gas Chromatography-Mass Spectrometry; D032411:Lippia / Q000737:chemistry*; D009822:Oils, Volatile / Q000737:chemistry*; D010636:Phenols / Q000032:analysis; D025341:Principal Component Analysis; D012717:Sesquiterpenes / Q000032:analysis
chemical_list: D009822:Oils, Volatile; D010636:Phenols; D012717:Sesquiterpenes
keywords: Chemometrics; Chemotypes; Essential oil; Germplasm conservation; Hierarchical cluster analysis (HCA); Lippia graveolens; Principal component analysis (PCA)