Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer

• Published in: The New phytologist Vol. 190; no. 3; pp. 709 - 723
• Main Authors: Lens, Frederic, Sperry, John S., Christman, Mairgareth A., Choat, Brendan, Rabaey, David, Jansen, Steven
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-05-2011; John Wiley & Sons; Wiley Subscription Services, Inc
• Subjects: Acer; Acer - anatomy & histology; Acer - cytology; Acer - physiology; Acer - ultrastructure; Anatomy; Cavitation; Cavitation flow; Cavitation resistance; Correlation; Electron microscopy; Fluid dynamics; Fluid flow; fluid mechanics; Hydraulic conductivity; Hydraulics; Hypotheses; Mechanical properties; Models, Biological; Organ Specificity; Phylogeny; pit structure; Plants; Porosity; Pressure; Quantitative Trait, Heritable; rare pit hypothesis; scanning electron microscopy; Specific conductivity; Structure-function relationships; Thickness; Tissue; Transmission electron microscopy; tree cavities; vessel distribution; vessel wall thickenings; Vessels; Vulnerability; Water - physiology; Wood; Wood - anatomy & histology; Wood - cytology; Wood - ultrastructure; wood anatomy; Wood density; Wood structure; Xylem; Xylem - anatomy & histology; Xylem - cytology; Xylem - physiology; Xylem - ultrastructure; Xylem vessels
• ISSN: 0028-646X; 1469-8137; 1469-8137
• DOI: 10.1111/j.1469-8137.2010.03518.x

• Vulnerability to cavitation and conductive efficiency depend on xylem anatomy. We tested a large range of structure-function hypotheses, some for the first time, within a single genus to minimize phylogenetic ‘noise' and maximize detection of functionally relevant variation. • This integrative study combined in-depth anatomical observations using light, scanning and transmission electron microscopy of seven Acer taxa, and compared these observations with empirical measures of xylem hydraulics. • Our results reveal a 2 MPa range in species' mean cavitation pressure (MCP). MCP was strongly correlated with intervessel pit structure (membrane thickness and porosity, chamber depth), weakly correlated with pit number per vessel, and not related to pit area per vessel. At the tissue level, there was a strong correlation between MCP and mechanical strength parameters, and some of the first evidence is provided for the functional significance of vessel grouping and thickenings on inner vessel walls. In addition, a strong trade-off was observed between xylem-specific conductivity and MCP. Vessel length and intervessel wall characteristics were implicated in this safety-efficiency trade-off. • Cavitation resistance and hydraulic conductivity in Acer appear to be controlled by a very complex interaction between tissue, vessel network and pit characteristics.