New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis L.
Article first published online: 22 JUL 2004
Plant, Cell & Environment
Volume 27, Issue 8, pages 1065–1076, August 2004
How to Cite
SALLEO, S., LO GULLO, M. A., TRIFILÒ, P. and NARDINI, A. (2004), New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis L. Plant, Cell & Environment, 27: 1065–1076. doi: 10.1111/j.1365-3040.2004.01211.x
- Issue published online: 22 JUL 2004
- Article first published online: 22 JUL 2004
- Received 6 February 2004; received in revised form 29 March 2004; accepted for publication13 April 2004
- Laurus nobilis L.;
- xylem embolism;
- starch content
Xylem recovery from embolism was studied in Laurus nobilis L. stems that were induced to cavitate by combining negative xylem pressure potentials (PX = −1.1 MPa) with positive air pressures (PC) applied using a pressure collar. Xylem refilling was measured by recording the percentage loss of hydraulic conductance (PLC) with respect to the maximum 2 min, 20 min and 15 h after pressure release. Sodium orthovanadate (an inhibitor of many ATP-ases) strongly inhibited xylem refilling while fusicoccin (a stimulator of the plasma membrane H+-ATPase) promoted complete embolism reversal. So, the refilling process was interpreted to result from energy-dependent mechanisms. Stem girdling induced progressively larger inhibition to refilling the nearer to the embolized stem segment phloem was removed. The starch content of wood parenchyma was estimated as percentages of ray and vasicentric cells with high starch content with respect to the total, before and after stem embolism was induced. A closely linear positive relationship was found to exist between recovery from PLC and starch hydrolysis. This, was especially evident in vasicentric cells. A mechanism for xylem refilling based upon starch to sugar conversion and transport into embolized conduits, assisted by phloem pressure-driven radial mass flow is proposed.