Bouche, PS and Delzon, S and Choat, B and Badel, E and Brodribb, TJ and Burlett, R and Cochard, H and Charra-Vaskou, K and Lavigne, B and Li, S and Mayr, S and Morris, H and Torrez-Ruiz, JM and Zufferey, V and Jansen, S, Are needles of Pinus pinaster more vulnerable to xylem embolism than branches? New insights from X-ray computed tomography, Plant, Cell and Environment, 39, (4) pp. 860-870. ISSN 0140-7791 (2016) [Refereed Article]
Copyright 2015 John Wiley & Sons Ltd
Plants can be highly segmented organisms with an independently redundant design of organs. In the context of plant hydraulics, leaves may be less embolism resistant than stems, allowing hydraulic failure to be restricted to distal organs that can be readily replaced.
We quantified drought-induced embolism in needles and stems of Pinus pinaster using high-resolution computed tomography (HRCT). HRCT observations of needles were compared with the rehydration kinetics method to estimate the contribution of extra-xylary pathways to declining hydraulic conductance.
High-resolution computed tomography images indicated that the pressure inducing 50% of embolized tracheids was similar between needle and stem xylem (P50 needle xylem = −3.62 MPa, P50 stem xylem = −3.88 MPa). Tracheids in both organs showed no difference in torus overlap of bordered pits. However, estimations of the pressure inducing 50% loss of hydraulic conductance at the whole needle level by the rehydration kinetics method were significantly higher (P50 needle = −1.71 MPa) than P50 needle xylem derived from HRCT.
The vulnerability segmentation hypothesis appears to be valid only when considering hydraulic failure at the entire needle level, including extra-xylary pathways. Our findings suggest that native embolism in needles is limited and highlight the importance of imaging techniques for vulnerability curves.
|Item Type:||Refereed Article|
|Keywords:||conifer, hydraulic failures, embolised tracheids, wall deformation, direct visualization of water content|
|Research Division:||Biological Sciences|
|Research Group:||Plant Biology|
|Research Field:||Plant Physiology|
|Objective Division:||Expanding Knowledge|
|Objective Group:||Expanding Knowledge|
|Objective Field:||Expanding Knowledge in the Environmental Sciences|
|Author:||Brodribb, TJ (Dr Tim Brodribb)|
|Funding Support:||Australian Research Council (DP120101686)|
|Web of Science® Times Cited:||24|
|Deposited By:||Plant Science|
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