title: Stem xylem resistance to cavitation is related to xylem structure but not to growth and water-use efficiency at the within-population level in Populus nigra L.
abstract: Xylem resistance to drought-induced cavitation is a key trait of plant water relations. This study assesses the genetic variation expressed for stem cavitation resistance within a population of a riparian species, the European black poplar (Populus nigra L.), and explores its relationships with xylem anatomy, water-use efficiency (WUE), and growth. Sixteen structural and physiological traits related to cavitation resistance, xylem anatomy, growth, bud phenology, and WUE were measured on 33 P. nigra genotypes grown under optimal irrigation in a 2-year-old clonal experiment in a nursery. Significant genetic variation was expressed for the xylem tension inducing 50% loss of hydraulic conductivity (Ψ50) within the studied population, as attested by the high value of broad-sense heritability estimated for this trait (H (2) ind = 0.72). Stem cavitation resistance was associated with xylem structure: the more cavitation-resistant genotypes exhibited lower hydraulic efficiency and higher mechanical reinforcement as assessed from stem xylem cross sections. By contrast, Ψ50 was not significantly related to shoot height increment, total above-ground dry mass, or bulk leaf carbon isotope discrimination, a proxy for intrinsic WUE. These findings indicate that the trade-offs between xylem resistance to cavitation, hydraulic efficiency, and mechanical reinforcement can occur at the within-population level. Given that the studied genotypes were exposed to the same environmental conditions and evolutionary drivers in situ, the trade-offs detected at this scale are expected to reflect true functional relationships.
authors.affiliation: Université d'Orléans, INRA, EA 1207, Laboratoire de Biologie des Ligneux et des Grandes Cultures, F-45067 Orléans France INRA, UR 0588 'Amélioration, Génétique et Physiologie Forestières' (AGPF), Centre de Recherche Val de Loire, CS 40001 Ardon, F-45075 Orléans Cedex 2, France.
authors.forename: Justine
authors.initials: J
authors.lastname: Guet
authors.affiliation: Université d'Orléans, INRA, EA 1207, Laboratoire de Biologie des Ligneux et des Grandes Cultures, F-45067 Orléans France.
authors.forename: Régis
authors.initials: R
authors.lastname: Fichot
authors.affiliation: Université d'Orléans, INRA, EA 1207, Laboratoire de Biologie des Ligneux et des Grandes Cultures, F-45067 Orléans France INRA, UR 0588 'Amélioration, Génétique et Physiologie Forestières' (AGPF), Centre de Recherche Val de Loire, CS 40001 Ardon, F-45075 Orléans Cedex 2, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Lédée
authors.affiliation: INRA, UR 0588 'Amélioration, Génétique et Physiologie Forestières' (AGPF), Centre de Recherche Val de Loire, CS 40001 Ardon, F-45075 Orléans Cedex 2, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Laurans
authors.affiliation: INRA, Université Blaise Pascal, UMR 547 PIAF, F-63100 Clermont-Ferrand, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Cochard
authors.affiliation: INRA, Université de Bordeaux, UMR 1202 BIOGECO, F-33405 Talence, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Delzon
authors.affiliation: INRA, UR 0588 'Amélioration, Génétique et Physiologie Forestières' (AGPF), Centre de Recherche Val de Loire, CS 40001 Ardon, F-45075 Orléans Cedex 2, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Bastien
authors.affiliation: Université d'Orléans, INRA, EA 1207, Laboratoire de Biologie des Ligneux et des Grandes Cultures, F-45067 Orléans France franck.brignolas@univ-orleans.fr.
authors.forename: Franck
authors.initials: F
authors.lastname: Brignolas
mesh_terms: D001696:Biomechanical Phenomena; D055864:Droughts; D014644:Genetic Variation; D018547:Plant Stems / Q000033:anatomy & histology / Q000166:cytology; D032107:Populus / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D014867:Water / Q000502:physiology*; D052584:Xylem / Q000033:anatomy & histology / Q000166:cytology
chemical_list: D014867:Water
keywords: Bud phenology; Populus nigra; bulk leaf carbon isotope discrimination; drought-induced cavitation; functional trade-offs; growth; riparian species; water-use efficiency; within-population genetic variation; xylem structure.