Percepción do risco de herbivoría en dous piñeiros de interese forestal: cambios na química defensiva ; Perception of biotic risk in the neighbourhood by young pine trees of two forestry species: changes in the concentration of chemical defences ; Percepción del riesgo de herbivoría en dos pinos de interés forestal: cambios en la química defensiva

90 páginas.- Memoria presentada para el Proyecto fin de carrera en la Escuela Universitaria de Ingeniería Técnica Forestal de Pontevedra, Universidad de Vigo. ; [EN] Most plants deliver continuously complex admixtures of volatile organic compounds (VOCs) to the surrounding atmosphere that may change in response to biotic aggressions. Recent papers have shown that those induced VOC’s could serve for within-plant signalling of distant tissues, also for attracting herbivore predators and parasitoids, but also may be perceived by other plants in the neighbourhood as danger signals activating their defensive system. Little is know about these defensive abilities in Maritime Pine (P. pinaster) and Radiata Pine (P. radiata), two pine species with major relevance for forestry in northern Spain. Here we studied the ability of pine saplings of those species (‘receptor’ plants) growing during 40 days in experimental greenhouses for perceiving the herbivory suffered by neighbour plants (‘emitters’) by the large pine weevil (Hylobius abietis), and for changing their defensive phenotypes accordingly. In particular, we quantified the content on non-volatile resin and total polyphenolics in the needles and in the upper and lower part of the stems of receptor plants just after the growing period (constitutive) and after being exposed by herbivory by the weevil for 5 days (induced defences). Constitutive defences in the stem showed a marked within-plant distribution pattern, with more resin in the upper part a more polyphenolics in the lower part of the stem in both pine species. We found a significant 66% increase in the constitutive concentration of non-volatile resin in the upper part of P. radiata saplings grown in presence of herbivory in their neighbourhood. However we did not found changes in polyphenolics or other tissues in P. radiata neither in P. pinaster. Plants growing in the neighbourhood of attacked plants showed significant or marginally significant induced susceptibility responses when exposed to real herbivory, ...