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Functional repair of embolized vessels in maize roots after temporal drought stress, as demonstrated by magnetic resonance imaging
Author(s) -
Kaufmann Ilja,
SchulzeTill Thomas,
Schneider Heike U.,
Zimmermann Ulrich,
Jakob Peter,
Wegner Lars H.
Publication year - 2009
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2009.02919.x
Subject(s) - xylem , nuclear magnetic resonance , vascular bundle , cavitation , chemistry , turgor pressure , biophysics , magnetic resonance imaging , materials science , biology , botany , mechanics , physics , medicine , radiology
Summary• 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.