Is xylem of angiosperm leaves less resistant to embolism than branches? Insights from microCT, hydraulics, and anatomy

Matthias Klepsch, Ya Zhang, Martyna M. Kotowska, Laurent J. Lamarque, Markus Nolf, Bernhard Schuldt, José M. Torres-Ruiz, De Wen Qin, Brendan Choat, Sylvain Delzon, Christine Scoffoni, Kun Fang Cao, Steven Jansen

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    32 Citations (Scopus)
    45 Downloads (Pure)

    Abstract

    According to the hydraulic vulnerability segmentation hypothesis, leaves are more vulnerable to decline of hydraulic conductivity than branches, but whether stem xylem is more embolism resistant than leaves remains unclear. Drought-induced embolism resistance of leaf xylem was investigated based on X-ray microcomputed tomography (microCT) for Betula pendula, Laurus nobilis, and Liriodendron tulipifera, excluding outside-xylem, and compared with hydraulic vulnerability curves for branch xylem. Moreover, bordered pit characters related to embolism resistance were investigated for both organs. Theoretical P50 values (i.e. the xylem pressure corresponding to 50% loss of hydraulic conductance) of leaves were generally within the same range as hydraulic P50 values of branches. P50 values of leaves were similar to branches for L. tulipifera (-2.01 versus -2.10 MPa, respectively), more negative for B. pendula (-2.87 versus -1.80 MPa), and less negative for L. nobilis (-6.4 versus -9.2 MPa). Despite more narrow conduits in leaves than branches, mean interconduit pit membrane thickness was similar in both organs, but significantly higher in leaves of B. pendula than in branches. This case study indicates that xylem shows a largely similar embolism resistance across leaves and branches, although differences both within and across organs may occur, suggesting interspecific variation with regard to the hydraulic vulnerability segmentation hypothesis.

    Original languageEnglish
    Pages (from-to)5611-5623
    Number of pages13
    JournalJournal of Experimental Botany
    Volume69
    Issue number22
    DOIs
    Publication statusPublished - 1 Dec 2018

    Bibliographical note

    Copyright the Author(s) 2018. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

    Keywords

    • Bordered pit
    • branch
    • embolism
    • hydraulic segmentation
    • leaf
    • microCT
    • pit membrane
    • xylem
    • MicroCT
    • Xylem
    • Embolism
    • Pit membrane
    • Branch
    • Leaf
    • Hydraulic segmentation

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