Premium
Plumbing the depths: extracellular water storage in specialized leaf structures and its functional expression in a three‐domain pressure –volume relationship
Author(s) -
Nguyen Hoa T.,
Meir Patrick,
Wolfe Joe,
Mencuccini Maurizio,
Ball Marilyn C.
Publication year - 2017
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12788
Subject(s) - turgor pressure , plasmolysis , osmotic pressure , biophysics , water content , apoplast , water transport , extracellular , chemistry , osmoregulation , xylem , botany , avicennia marina , dehydration , symplast , salinity , biology , cell wall , water flow , soil science , biochemistry , ecology , mangrove , environmental science , geology , geotechnical engineering
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 −2 s −1 for 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.