Testing the Münch hypothesis of long distance phloem transport in plants

  1. Michael Knoblauch  Is a corresponding author
  2. Jan Knoblauch
  3. Daniel L Mullendore
  4. Jessica A Savage
  5. Benjamin A Babst
  6. Sierra D Beecher
  7. Adam C Dodgen
  8. Kaare H Jensen
  9. Noel Michele Holbrook
  1. Washington State University, United States
  2. Harvard University, United States
  3. University of Arkansas at Monticello, United States
  4. Technical University of Denmark, Denmark

Abstract

Long distance transport in plants occurs in sieve tubes of the phloem. The pressure flow hypothesis introduced by Ernst Münch in 1930 describes a mechanism of osmotically generated pressure differentials that are supposed to drive the movement of sugars and other solutes in the phloem, but this hypothesis has long faced major challenges. The key issue is whether the conductance of sieve tubes, including sieve plate pores, is sufficient to allow pressure flow. We show that with increasing distance between source and sink, sieve tube conductivity and turgor increases dramatically in Ipomoea nil. Our results provide strong support for the Münch hypothesis, while providing new tools for the investigation of one of the least understood plant tissues.

Article and author information

Author details

  1. Michael Knoblauch

    School of Biological Sciences, Washington State University, Pullman, United States
    For correspondence
    knoblauch@wsu.edu
    Competing interests
    The authors declare that no competing interests exist.
  2. Jan Knoblauch

    School of Biological Sciences, Washington State University, Pullman, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Daniel L Mullendore

    School of Biological Sciences, Washington State University, Pullman, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Jessica A Savage

    Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Benjamin A Babst

    School of Forestry and Natural Resources, University of Arkansas at Monticello, Monticello, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Sierra D Beecher

    School of Biological Sciences, Washington State University, Pullman, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Adam C Dodgen

    School of Biological Sciences, Washington State University, Pullman, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Kaare H Jensen

    Department of Physics, Technical University of Denmark, Lyngby, Denmark
    Competing interests
    The authors declare that no competing interests exist.
  9. Noel Michele Holbrook

    Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Christian S Hardtke, University of Lausanne, Switzerland

Publication history

  1. Received: February 18, 2016
  2. Accepted: June 1, 2016
  3. Accepted Manuscript published: June 2, 2016 (version 1)
  4. Version of Record published: July 15, 2016 (version 2)

Copyright

© 2016, Knoblauch et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Michael Knoblauch
  2. Jan Knoblauch
  3. Daniel L Mullendore
  4. Jessica A Savage
  5. Benjamin A Babst
  6. Sierra D Beecher
  7. Adam C Dodgen
  8. Kaare H Jensen
  9. Noel Michele Holbrook
(2016)
Testing the Münch hypothesis of long distance phloem transport in plants
eLife 5:e15341.
https://doi.org/10.7554/eLife.15341
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