title: The Impact of Competition and Allelopathy on the Trade-Off between Plant Defense and Growth in Two Contrasting Tree Species.
abstract: In contrast to plant-animal interactions, the conceptual framework regarding the impact of secondary metabolites in mediating plant-plant interference is currently less well defined. Here, we address hypotheses about the role of chemically-mediated plant-plant interference (i.e., allelopathy) as a driver of Mediterranean forest dynamics. Growth and defense abilities of a pioneer (Pinus halepensis) and a late-successional (Quercus pubescens) Mediterranean forest species were evaluated under three different plant interference conditions: (i) allelopathy simulated by application of aqueous needle extracts of Pinus, (ii) resource competition created by the physical presence of a neighboring species (Pinus or Quercus), and (iii) a combination of both allelopathy and competition. After 24 months of experimentation in simulated field conditions, Quercus was more affected by plant interference treatments than was Pinus, and a hierarchical response to biotic interference (allelopathy < competition < allelopathy + competition) was observed in terms of relative impact on growth and plant defense. Both species modulated their respective metabolic profiles according to plant interference treatment and thus their inherent chemical defense status, resulting in a physiological trade-off between plant growth and production of defense metabolites. For Quercus, an increase in secondary metabolite production and a decrease in plant growth were observed in all treatments. In contrast, this trade-off in Pinus was only observed in competition and allelopathy + competition treatments. Although Pinus and Quercus expressed differential responses when subjected to a single interference condition, either allelopathy or competition, species responses were similar or positively correlated when strong interference conditions (allelopathy + competition) were imposed.
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale - Aix Marseille Université - Centre National de la Recherche Scientifique - IRD - Avignon Université Marseille, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Fernandez
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale - Aix Marseille Université - Centre National de la Recherche Scientifique - IRD - Avignon Université Marseille, France.
authors.forename: Yogan
authors.initials: Y
authors.lastname: Monnier
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale - Aix Marseille Université - Centre National de la Recherche Scientifique - IRD - Avignon Université Marseille, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Santonja
authors.affiliation: Laboratoire d'Ecologie Alpine - Université de Savoie-Mont-Blanc Chambéry, France.
authors.forename: Christiane
authors.initials: C
authors.lastname: Gallet
authors.affiliation: Graham Centre for Agricultural Innovation- Charles Sturt University Wagga Wagga, NSW, Australia.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Weston
authors.affiliation: Institut National de Recherche en Sciences et Technologies Pour l'Environnement et l'Agriculture Aix-en-Provence, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Prévosto
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale - Aix Marseille Université - Centre National de la Recherche Scientifique - IRD - Avignon Université Marseille, France.
authors.forename: Amélie
authors.initials: A
authors.lastname: Saunier
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale - Aix Marseille Université - Centre National de la Recherche Scientifique - IRD - Avignon Université Marseille, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Baldy
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale - Aix Marseille Université - Centre National de la Recherche Scientifique - IRD - Avignon Université Marseille, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Bousquet-Mélou
keywords: Pinus halepensis; Quercus pubescens; allelopathy; competition; ecometabolomics; metabolic profiling; phenotypic response; secondary metabolism