%0 Journal Article
%A Kaufmann, I.
%A Schulze-Till, T.
%A Schneider, H. U.
%A Zimmermann, U.
%A Jakob, P.
%A Wegner, L. H.
%T Functional repair of embolized vessels in maize roots after temporal drought stress, as demonstrated by magnetic  resonance imaging
%J The new phytologist
%V 184
%@ 0028-646X
%C Oxford [u.a.]
%I Wiley-Blackwell
%M PreJuSER-964
%P 245 - 256
%D 2009
%Z Record converted from VDB: 12.11.2012
%X 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.
%K Droughts
%K Magnetic Resonance Spectroscopy
%K Models, Biological
%K Plant Exudates: metabolism
%K Plant Roots: cytology
%K Plant Roots: physiology
%K Plant Transpiration
%K Seedling: physiology
%K Spin Labels
%K Stress, Physiological
%K Time Factors
%K Xylem: physiology
%K Zea mays: physiology
%K Plant Exudates (NLM Chemicals)
%K Spin Labels (NLM Chemicals)
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:19563443
%U <Go to ISI:>//WOS:000269541600023
%R 10.1111/j.1469-8137.2009.02919.x
%U https://juser.fz-juelich.de/record/964