Title: Leaf xylem embolism, detected acoustically and by cryo-SEM, corresponds to decreases in leaf hydraulic conductance in four evergreen species
Author: Johnson, Daniel M.; Meinzer, Frederick C.; Woodruff, David R.; McCulloh, Katherine A.;
Source: Plant, Cell and Environment
Publication Series: Scientific Journal (JRNL)
Hydraulic conductance of leaves (Kleaf) typically decreases with increasing water stress. However, the extent to which the decrease in Kleaf is due to xylem cavitation, conduit deformation, or changes in the extra-xylary pathway is unclear, We measured Kleaf concurrently with ultrasonic acoustic emission (UAE) in dehydrating leaves of two vessel-bearing and two tracheid-bearlng species to determine whether declining Kleaf was associated with an accumulation of cavitation events. In addition, images of leaf internal structure were captured using cryo-scanning electron microscopy, which allowed detection of empty versus full and also deformed conduits. Decreases in Kleaf were closely associated with accumulated UAE and the percentage of empty conduits. The mean amplitude of UAEs was tightly correlated with mean conduit diameter (R2 = 0.94, P = 0.018). These results suggest that water stress-induced decreases in Kleaf in these species are directly related to xylem embolism.
Keywords: cavitation, drought stress, transpiration, water potential
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Johnson, Daniel M.; Meinzer, Frederick C.; Woodruff, David R.; McCulloh, Katherine A. 2009. Leaf xylem embolism, detected acoustically and by cryo-SEM, corresponds to decreases in leaf hydraulic conductance in four evergreen species. Plant, Cell and Environment. 32:828-836.
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