title: Plumbing the depths: extracellular water storage in specialized leaf structures and its functional expression in a three-domain pressure -volume relationship.
abstract: A three-domain pressure-volume relationship (PV curve) was studied in relation to leaf anatomical structure during dehydration in the grey mangrove, Avicennia marina. In domain 1, relative water content (RWC) declined 13% with 0.85 MPa decrease in leaf water potential, reflecting a decrease in extracellular water stored primarily in trichomes and petiolar cisternae. In domain 2, RWC decreased by another 12% with a further reduction in leaf water potential to -5.1 MPa, the turgor loss point. Given the osmotic potential at full turgor (-4.2 MPa) and the effective modulus of elasticity (~40 MPa), domain 2 emphasized the role of cell wall elasticity in conserving cellular hydration during leaf water loss. Domain 3 was dominated by osmotic effects and characterized by plasmolysis in most tissues and cell types without cell wall collapse. Extracellular and cellular water storage could support an evaporation rate of 1 mmol m-2s-1for up to 54 and 50 min, respectively, before turgor loss was reached. This study emphasized the importance of leaf anatomy for the interpretation of PV curves, and identified extracellular water storage sites that enable transient water use without substantive turgor loss when other factors, such as high soil salinity, constrain rates of water transport.
authors.affiliation: Plant Science Division, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia.
authors.forename: Hoa T
authors.initials: HT
authors.lastname: Nguyen
authors.affiliation: Plant Science Division, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia.|School of GeoSciences, University of Edinburgh, Crew Building, West Mains Road, Edinburgh, EH9 3JN, UK.
authors.forename: Patrick
authors.initials: P
authors.lastname: Meir
authors.affiliation: School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.
authors.forename: Joe
authors.initials: J
authors.lastname: Wolfe
authors.affiliation: School of GeoSciences, University of Edinburgh, Crew Building, West Mains Road, Edinburgh, EH9 3JN, UK.|ICREA at CREAF, Universidad Autonoma de Barcelona, Cerdanyola del Valles, 08290, Barcelona, Spain.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mencuccini
authors.affiliation: Plant Science Division, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia.
authors.forename: Marilyn C
authors.initials: MC
authors.lastname: Ball
mesh_terms: D032407:Avicennia / Q000033:anatomy & histology / Q000502:physiology*; D020285:Cryoelectron Microscopy; D009995:Osmosis; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000378:metabolism* / Q000648:ultrastructure; D011134:Polysaccharides / Q000032:analysis; D064201:Trichomes / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D011134:Polysaccharides; D014867:Water
keywords: PV curve; cisternae; dehydration; leaf water capacitance; mangrove; plasmolysis; trichomes