Functional repair of embolized vessels in maize roots after temporal drought stress, as demonstrated by magnetic resonance imaging
Article first published online: 26 JUN 2009
© The Authors (2009). Journal compilation © New Phytologist (2009)
Volume 184, Issue 1, pages 245–256, October 2009
How to Cite
Kaufmann, I., Schulze-Till, T., Schneider, H. U., Zimmermann, U., Jakob, P. and Wegner, L. H. (2009), Functional repair of embolized vessels in maize roots after temporal drought stress, as demonstrated by magnetic resonance imaging. New Phytologist, 184: 245–256. doi: 10.1111/j.1469-8137.2009.02919.x
- Issue published online: 2 SEP 2009
- Article first published online: 26 JUN 2009
- Received: 9 March 2009Accepted: 29 April 2009
- collapse of xylem vessels;
- drought stress;
- flow imaging;
- magnetic resonance (MR) imaging (microscopy);
- xylem refilling;
- Zea mays (maize)
- • Xylem sap under high tension is in a metastable state and tends to cavitate, frequently leading to an interruption of the continuous water columns. Mechanisms of cavitation repair are controversially discussed.
- • Magnetic resonance (MR) imaging provides a noninvasive, high spatial and temporal resolution approach to monitor xylem cavitation, refilling, and functionality.
- • Spin density maps of drought-stressed maize taproots were recorded to localize cavitation events and to visualize the refilling processes; c. 2 h after release of the nutrient solution from the homemade MR imaging cuvette that received the root, late metaxylem vessels started to cavitate randomly as identified by a loss of signal intensity. After c. 6 h plants were rewatered, leading to a repair of water columns in five out of eight roots. Sap ascent during refilling, monitored with multislice MR imaging sequences, varied between 0.5 mm min−1 and 3.3 mm min−1. Flow imaging of apparently refilled vessels was performed to test for functional repair. Occasionally, a collapse of xylem vessels under tension was observed; this collapse was reversible upon rewatering.
- • Refilling was an all-or-none process only observed under low-light conditions. Absence of flow in some of the apparently refilled vessels indicates that functionality was not restored in these particular vessels, despite a recovery of the spin density signal.