Indirect Evidence for Genetic Differentiation in Vulnerability to Embolismin Pinus halepensis

Rakefet David-Schwartz (1) , Indira Paudel (2) , Mizrachi Mizrachi (1) , Sylvain Delzon (3) , Hervé Cochard (4) , Victor Lukyanov (2) , Eric Badel (5) , Gaëlle Capdeville (3) , Galina Shklar (1) , Shabtai Cohen (6)

1 Institute of Plant Sciences
2 Institute of Soil, Water and Environmental Sciences
3 BioGeCo - Biodiversité, Gènes & Communautés
4 PIAF - Laboratoire de Physique et Physiologie Intégratives de l'Arbre Fruitier et Forestier
5 PIAF - Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant
6 Insstitute of Soil, Water and Environmental Sciences

Climate change is increasing mean temperatures and in the eastern Mediterranean is expected to decrease annual precipitation. The resulting increase in aridity may be too rapid for adaptation of tree species unless their gene pool already possesses variation in drought resistance. Vulnerability to embolism, estimated by the pressure inducing 50% loss of xylem hydraulic conductivity (P-50), is strongly associated with drought stress resistance in trees. Yet, previous studies on various tree species reported low intraspecific genetic variation for this trait, and therefore limited adaptive capacities to increasing aridity. Here we quantified differences in hydraulic efficiency (xylem hydraulic conductance) and safety (resistance to embolism) in four contrasting provenances of Pinus halepensis (Aleppo pine) in a provenance trial, which is indirect evidence for genetic differences. Results obtained with three techniques (bench dehydration, centrifugation and X-ray micro-CT) evidenced significant differentiation with similar ranking between provenances. Inter-provenance variation in P50 correlated with pit anatomical properties (torus overlap and pit aperture size). These results suggest that adaptation of P. halepensis to xeric habitats has been accompanied by modifications of bordered pit function driven by variation in pit aperture. This study thus provides evidence that appropriate exploitation of provenance differences will allow continued forestry with P. halepensis in future climates of the Eastern Mediterranean.

Mots clés: embolism; xylem hydraulics; provenance trial; genetic variation; border; pit; torus-margo; water potential; xylem conductivity; chloroplast microsatellite markers; induced xylem embolism; water-stress; climate-change; aleppo pine; ecophysiological response; phenotypic plasticity; mediterranean pine; severe drought; pit structure; genetic variant; xylem; testing

Mots clés: embolisme; variation génétique; potentiel hydrique; xylème; essai

Domaines: Biologie végétale

Rakefet David-Schwartz, Indira Paudel, Mizrachi Mizrachi, Sylvain Delzon, Hervé Cochard, et al.. Indirect Evidence for Genetic Differentiation in Vulnerability to Embolismin Pinus halepensis. Frontiers in Plant Science, 2016, Frontiers in Plant Science, 468 p. ⟨hal-01535212⟩