title: Testing phenotypic trade-offs in the chemical defence strategy of Scots pine under growth-limiting field conditions.
abstract: Plants protect themselves from pathogens and herbivores through fine-tuned resource allocation, including trade-offs among resource investments to support constitutive and inducible defences. However, empirical research, especially concerning conifers growing under natural conditions, is still scarce. We investigated the complexity of constitutive and induced defences in a natural Scots pine (Pinus sylvestris L.) stand under growth-limiting conditions typical of alpine environments. Phenotypic trade-offs at three hierarchical levels were tested by investigating the behaviour of phenolic compounds and terpenoids of outer bark and phloem. We tested resource-derived phenotypic correlations between (i) constitutive and inducible defences vs tree ring growth, (ii) different constitutive defence metabolites and (iii) constitutive concentration and inducible variation of individual metabolites. Tree ring growth was positively correlated only with constitutive concentration of total terpenoids, and no overall phenotypic trade-offs between different constitutive defensive metabolites were found. At the lowest hierarchical level tested, i.e., at the level of relationship between constitutive and inducible variation of individual metabolites, we found that different compounds displayed different behaviours; we identified five different defensive metabolite response types, based on direction and strength of the response, regardless of tree age and growth rate. Therefore, under growth-limiting field conditions, Scots pine appears to utilize varied and complex outer bark and phloem defence chemistry, in which only part of the constitutive specialized metabolism is influenced by tree growth, and individual components do not appear to be expressed in a mutually exclusive manner in either constitutive or inducible metabolism.
authors.affiliation: Department of Plant Pathology, The Ohio State University, 201 Kottman Hall, 2021 Coffey Rd, Columbus, OH 43210, USA Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, Università di Padova, Agripolis, Legnaro, Padova 35020, Italy villari.2@osu.edu.
authors.forename: Caterina
authors.initials: C
authors.lastname: Villari
authors.affiliation: Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, Università di Padova, Agripolis, Legnaro, Padova 35020, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Faccoli
authors.affiliation: Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, Università di Padova, Agripolis, Legnaro, Padova 35020, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Battisti
authors.affiliation: Department of Plant Pathology, The Ohio State University, 201 Kottman Hall, 2021 Coffey Rd, Columbus, OH 43210, USA.
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Bonello
authors.affiliation: Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, Università di Padova, Agripolis, Legnaro, Padova 35020, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Marini
mesh_terms: D060467:Disease Resistance; D060434:Herbivory; D010636:Phenols / Q000378:metabolism*; D052585:Phloem / Q000737:chemistry*; D041605:Pinus sylvestris / Q000254:growth & development / Q000276:immunology / Q000502:physiology*; D024301:Plant Bark / Q000737:chemistry*; D010935:Plant Diseases / Q000209:etiology / Q000276:immunology; D057865:Plant Immunity; D013729:Terpenes / Q000378:metabolism*
chemical_list: D010636:Phenols; D013729:Terpenes
keywords: constitutive defence; induced defence; phenolics; resource allocation; ring growth; specialized metabolisms; terpenoids