Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism. - Archive ouverte HAL Access content directly
Journal Articles Proceedings of the National Academy of Sciences of the United States of America Year : 2012

Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism.

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Jianyong Sun
  • Function : Author
Alistair M Middleton
  • Function : Author
Andrew P French
  • Function : Author
Ethel Mendocilla Sato
  • Function : Author
Michael H Wilson
  • Function : Author
Ranjan Swarup
  • Function : Author
Ilkka Sairanen
  • Function : Author
Tom Beeckman
Jonathan M Garibaldi
  • Function : Author
Mark Estelle
Markus R Owen
  • Function : Author
Kris Vissenberg
  • Function : Author
  • PersonId : 881583
T Charlie Hodgman
  • Function : Author
Tony P Pridmore
  • Function : Author
Teva Vernoux

Abstract

Gravity profoundly influences plant growth and development. Plants respond to changes in orientation by using gravitropic responses to modify their growth. Cholodny and Went hypothesized over 80 years ago that plants bend in response to a gravity stimulus by generating a lateral gradient of a growth regulator at an organ's apex, later found to be auxin. Auxin regulates root growth by targeting Aux/IAA repressor proteins for degradation. We used an Aux/IAA-based reporter, domain II (DII)-VENUS, in conjunction with a mathematical model to quantify auxin redistribution following a gravity stimulus. Our multidisciplinary approach revealed that auxin is rapidly redistributed to the lower side of the root within minutes of a 90° gravity stimulus. Unexpectedly, auxin asymmetry was rapidly lost as bending root tips reached an angle of 40° to the horizontal. We hypothesize roots use a "tipping point" mechanism that operates to reverse the asymmetric auxin flow at the midpoint of root bending. These mechanistic insights illustrate the scientific value of developing quantitative reporters such as DII-VENUS in conjunction with parameterized mathematical models to provide high-resolution kinetics of hormone redistribution.

Dates and versions

cea-00848570 , version 1 (26-07-2013)

Identifiers

Cite

Leah R Band, Darren M Wells, Antoine Larrieu, Jianyong Sun, Alistair M Middleton, et al.. Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism.. Proceedings of the National Academy of Sciences of the United States of America, 2012, 109 (12), pp.4668-73. ⟨10.1073/pnas.1201498109⟩. ⟨cea-00848570⟩
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