Inter-regional variation on leaf surface defenses in native and non-native Centaurea solstitialis plants

Plant chemical defenses can be qualitative (toxins) to face generalist herbivores and quantitative (digestibility reducers) to specialists. Trichomes can produce chemicals, but also acts as a quantitative defense and in water loss. The shifting defense hypothesis (SDH) poses that invasive plants reduce the production of qualitative defenses against specialist herbivores because those are frequently absent in invaded regions, while increasing defenses against generalist herbivores. Chemical and physical leaf surface defensive traits could give information about direct plant–herbivore interaction in native and non-native regions. We studied leaf surface morphology and epicuticular chemistry of the invasive C. solstitialis in plants from native and non-native regions. Across regions, the main chemical components were sesquiterpene lactones, similar densities of sessile glandular trichomes and a variable number of large multicellular trichomes. Exotic plants face different sets of challenges in the new regions. In accordance with SDH, plants from non-native regions presented higher total sesquiterpene lactones concentrations (qualitative defense). Trichome density was possibly associated to differences in local climatic conditions. Sesquiterpene lactones are likely to play an important role on the invasion success of Centaurea. Leaf surface components provide meaningful information that should be consider in future studies to unravel the mechanisms involved in plant invasions.Fil: Sotes, Gastón J.. Universidad de Chile; Chile. Universidad de Concepción, Facultad de Ciencias Naturales y Oceanográficas, Departamento de Botánica; ChileFil: Cavieres, Lohengrin Alexis. Universidad de Concepción, Facultad de Ciencias Naturales y Oceanográficas, Departamento de Botánica; Chile. Universidad de Chile; ChileFil: Montesinos, Daniel. Universidad de Coimbra; PortugalFil: Pereira Coutinho, António Xavier. Universidad de Coimbra; PortugalFil: Peláez, Walter José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Martins Lopes, Susana Margarida. Universidad de Coimbra; PortugalFil: Vasconcelos Dias de Pinho e Melo, Teresa Margarida. Universidad de Coimbra; Portuga