Pressure–volume curves: revisiting the impact of negative turgor during cell collapse by literature review and simulations of cell micromechanics

• Published in: The New phytologist 2014-07, Vol.203 (2), p.378-387
• Main Authors: Ding, Yiting, Zhang, Yanxiang, Zheng, Quan‐Shui, Tyree, Melvin T
• Format: Article
• Language: English
• Subjects: Allium - cytology; Analysis; Aridity; Bulk modulus; Cell culture; Cell lines; Cell Size; Cell walls; collapse; Computer Simulation; Decompression chambers; Delta cells; Elasticity; Epidermal cells; Errors; Finite Element Analysis; Finite element method (FEM); habitats; Impact analysis; Leaves; Literature reviews; Micromechanics; Modeling; Modulus of elasticity; negative turgor; Osmosis; Osmotic pressure; Photovoltaic cells; Plant cells; Plant Cells - physiology; Plant Leaves - cytology; Plant Leaves - physiology; Pressure; pressure chamber; Pressure chambers; pressure–volume curves; rain forests; Rainforests; Robinia - cytology; Surveying; surveys; Turgor; Turgor pressure; Water loss; Water potential
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.12829

The Scholander–Hammel pressure chamber has been used in thousands of papers to measure osmotic pressure, πc, turgor pressure, Pₜ, and bulk modulus of elasticity, ε, of leaf cells by pressure–volume (PV) curve analysis. PV analysis has been questioned in the past. In this paper we use micromechanical analysis of leaf cells to examine the impact on PV curve analysis of negative turgor in living cells (Pₜ). Models predict negative Pₜ (−0.1 to −1.8 MPa) depending on leaf cell size and shape in agreement with experimental values reported by J. J. Oertli. Modeled PV curves have linear regions even when Pₜ is quite negative, contrary to the arguments of M.T. Tyree. Negative Pₜ is totally missed by PV curve analysis and results in large errors in derived πc and Pₜ but smaller errors in ε. A survey of leaf cell sizes vs habitat (arid, temperate, and rainforest), suggests that the majority of published PV curves result in errors of 0.1–1.8 MPa in derived πc and Pₜ, whereby the error increases with decreasing cell size. We propose that small cell size in leaves is an ecological adaptation that permits plants to endure negative values of water potential with relatively little water loss.