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Visualizing Drought Recovery in Plants Print
Thursday, 25 August 2011 15:34

How plants refill the vessels that transport water has been under debate for the last 30 years owing to the lack of an in vivo visualization tool at the appropriate temporal and spatial resolution. Now, data generated using high-resolution x-ray computed tomography (HRCT) at Beamline 8.3.2 provide the first visualization of the mechanism plants use to refill vessels, and show water droplets being pumped into air-filled vessels from the surrounding plant tissue, forcing the air bubbles back into solution.

The vessels that transport water through plants are vulnerable to blockage by gas bubbles that form during periods of drought. The ability to restore water flow in blocked vessels was a key adaptation in the colonization of land by plants and has allowed trees to push the limits of plant height to over 100 meters.

 

wine vessels

In vivo high-resolution x-ray computed tomography (HRCT) sections of a representative grapevine stem undergoing vessel refilling. Time-lapse longitudinal sections (A) showing the refilling of three adjacent vessels and the presence of water droplets on the inner vessel walls (hours indicated in each section). Bar = 200 μm. Trans-longitudinal section with vessel walls and droplets rendered in 3D (B). Trans-longitudinal section showing droplet details in four vessels at different stages of refilling (C), and the corresponding 3D volume rendering (D). Vessel on the far left shows evidence of failed refilling. Bars = 100 μm.

 

Our study provides the first direct evidence that the long standing Cohesion-Tension theory of water transport paradigm does not fully explain how water is transported in plants, and plants appear to regulate internal pressure gradients to refill empty vessels. These data represent a sea change in our understanding of plant hydraulics, and highlight a fundamentally important structure/function relationship that is common to all vascular plants.

 


Work performed on ALS Beamline 8.3.2

Citation: C.R. Brodersen, A.J. McElrone, Choat, B., M.A.. Matthews, and K. A. Shackel, "The Dynamics of Embolism Repair in Xylem: In Vivo Visualizations Using High-Resolution Computed Tomography," Plant Physiology, November 2010, Vol. 154, pp. 1088–1095

Web: http://www.plantphysiol.org/cgi/content/full/154/3/1088