Oxygen isotope enrichment of organic matter in Ricinus communis during the diel course and as affected by assimilate transport

Authors

  • Arthur Gessler,

    1. Environmental Biology Group; Research School of Biological Sciences, Australian National University, Canberra, Australia;
    2. School of Forest and Ecosystem Science, University of Melbourne, Water Street, Creswick, Victoria, Australia;
    3. Present address: Core Facility Metabolomics, Centre for Systems Biology (ZBSA) and Chair of Tree Physiology, University of Freiburg, Georges-Köhler Allee 53/54, 79085 Freiburg im-Bresigau, Germany
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  • Andreas D. Peuke,

    1. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney NSW 2052 Australia;
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  • Claudia Keitel,

    1. Environmental Biology Group; Research School of Biological Sciences, Australian National University, Canberra, Australia;
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  • Graham D. Farquhar

    1. Environmental Biology Group; Research School of Biological Sciences, Australian National University, Canberra, Australia;
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Author for correspondence: Arthur Gessler Tel: +49 761 2038310 Fax: +49 761 2038302 E-mail: arthur.gessler@sonne.uni-freiburg.de

Summary

  • • The oxygen isotope composition in leaf water and organic compounds in different plant tissues is useful for assessing the physiological performance of plants in their environment, but more information is needed on Δ18O variation during a diel course.
  • • Here, we assessed Δ18O of the organic matter in leaves, phloem and xylem in stem segments, and fine roots of Ricinus communis during a full diel cycle. Enrichment of newly assimilated organic matter in equilibrium with leaf water was calculated by applying a nonsteady-state evaporative enrichment model.
  • • During the light period, Δ18O of the water soluble organic matter pool in leaves and phloem could be explained by a 27‰ enrichment compared with leaf water enrichment. Leaf water enrichment influenced Δ18O of phloem organic matter during the night via daytime starch synthesis and night-time starch remobilization. Phloem transport did not affect Δ18O of phloem organic matter.
  • • Diel variation in Δ18O in organic matter pools can be modeled, and oxygen isotopic information is not biased during transport through the plant. These findings will aid field studies that characterize environmental influences on plant water balance using Δ18O in phloem organic matter or tree rings.

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