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Abstract Detail


Ecophysiology

McKown, Athena D. [1], Cochard, Hervé [2], Sack, Lawren [1].

Decoding the Leaf Venation Architecture: Testing Hydraulic Design Features with a Spatially Explicit Model.

Many advances in understanding leaf architecture have been made in the past several years. However, the physiological role of venation architecture is less well understood. Using the K_leaf computer modeling program, which constructs a spatially explicit leaf from inputs of real vein densities and vein conductivities, simulations were run to elucidate design principles of leaf venation and the functional consequences of its diversity. Aspects of venation architecture were manipulated in multiple scenarios to test impacts on hydraulic conductance of xylem and the whole-leaf (Kleaf and Kxylem respectively), to address evolutionary and ecological questions. Scenarios tested included examination of the roles of: 1. hierarchy in vein systems; 2. variation across vein orders in xylem conductivity; 3. major vein tapering; and 4. vein density. Further, two versions of the model were used, one with a fully integrated major vein system, and the second including sectoriality of the vessels in primary and secondary veins. Results of the model show that in the absence of vein order hierarchy, Kleaf increases linearly with vein conductivity. However, in hierarchical systems, changes in vein conductivity have reduced impact on Kxylem and Kleaf with increasing vein order from the midrib to the minor veins. Systems with tapered vessels in the major veins performed equally to systems without tapering, demonstrating that tapering can save on construction costs without reducing leaf hydraulic capacity. Increasing leaf vein density strongly increased Kxylem and Kleaf. The role of these design principles of leaf venation architecture in the diversification, conservation and convergence of xylem and venation traits across flowering plants will be discussed. Ongoing work with the K_leaf model will assess the impact of different venation architectures on pressure distributions across the leaf, as well as on leaf tolerance of cavitation and vein damage.


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1 - University of California, Los Angeles, Ecology and Evolutionary Biology, 621 Charles E. Young Drive, Los Angeles, CA, 90095, USA
2 - UMR INRA and UBP PIAF, 234 Av du Brézet, Clermont-Ferrand, F-63100, France

Keywords:
leaf venation
leaf hydraulics
Kleaf
Kxylem.

Presentation Type: Oral Paper:Papers for Topics
Session: 29
Location: 211/SUB
Date: Tuesday, July 29th, 2008
Time: 8:30 AM
Number: 29003
Abstract ID:850


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