title: Plasticity of vulnerability to leaf hydraulic dysfunction during acclimation to drought in grapevines: an osmotic-mediated process.
abstract: Previous studies have reported correlation of leaf hydraulic vulnerability with pressure-volume parameters related to cell turgor. This link has been explained on the basis of the effects of turgor on connectivity among cells and tissue structural integrity, which affect leaf water transport. In this study, we tested the hypothesis that osmotic adjustment to water stress would shift the leaf vulnerability curve toward more negative water potential (Ψ leaf ) by increasing turgor at low Ψ leaf . We measured leaf hydraulic conductance (K leaf ), K leaf vulnerability [50 and 80% loss of K leaf (P50 and P80 ); |Ψ leaf | at 50 and 80% loss of K leaf , respectively), bulk leaf water relations, leaf gas exchange and sap flow in two Vitis vinifera cultivars (Tempranillo and Grenache), under two water treatments. We found that P50 , P80 and maximum K leaf decreased seasonally by more than 20% in both cultivars and watering treatments. However, K leaf at 2 MPa increased threefold, while osmotic potential at full turgor and turgor loss point decreased. Our results indicate that leaf resistance to hydraulic dysfunction is seasonally plastic, and this plasticity may be mediated by osmotic adjustment.
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca, 07122, Spain.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Martorell
authors.forename: Hipolito
authors.initials: H
authors.lastname: Medrano
authors.forename: Magdalena
authors.initials: M
authors.lastname: Tomàs
authors.forename: José M
authors.initials: JM
authors.lastname: Escalona
authors.forename: Jaume
authors.initials: J
authors.lastname: Flexas
authors.forename: Antonio
authors.initials: A
authors.lastname: Diaz-Espejo
mesh_terms: D000064:Acclimatization; D003681:Dehydration; D055864:Droughts; D009995:Osmosis; D018515:Plant Leaves / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D027843:Vitis / Q000502:physiology*