This title appears in the Scientific Report : 2013 

Hydrodynamics of steady state phloem transport with radial leakage of solute
Cabrita, Paulo
Thorpe, Michael / Huber, Gregor (Corresponding author)
Pflanzenwissenschaften; IBG-2
Frontiers in plant science, 4 (2013) 531, S. 1-16
Lausanne Frontiers Media 2013
24409189
10.3389/fpls.2013.00531
Journal Article
Sustainable Bioproduction
OpenAccess
Please use the identifier: http://dx.doi.org/10.3389/fpls.2013.00531 in citations.
Please use the identifier: http://hdl.handle.net/2128/16204 in citations.
Long-distance phloem transport occurs under a pressure gradient generated by the osmotic exchange of water associated with solute exchange in source and sink regions. But these exchanges also occur along the pathway, and yet their physiological role has almost been ignored in mathematical models of phloem transport. Here we present a steady state model for transport phloem which allows solute leakage, based on the Navier-Stokes and convection-diffusion equations which describe fluid motion rigorously. Sieve tube membrane permeability Ps for passive solute exchange (and correspondingly, membrane reflection coefficient) influenced model results strongly, and had to lie in the bottom range of the values reported for plant cells for the results to be realistic. This smaller permeability reflects the efficient specialization of sieve tube elements, minimizing any diffusive solute loss favored by the large concentration difference across the sieve tube membrane. We also found there can be a specific reflection coefficient for which pressure profiles and sap velocities can both be similar to those predicted by the Hagen-Poiseuille equation for a completely impermeable tube.