Title
Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism Root gravitropism is regulated by a transient lateral auxin gradient controlled by a tipping-point mechanism
Author
Faculty/Department
Faculty of Sciences. Biology
Publication type
article
Publication
Washington, D.C. ,
Subject
Biology
Engineering sciences. Technology
Source (journal)
Proceedings of the National Academy of Sciences of the United States of America. - Washington, D.C.
Volume/pages
109(2012) :12 , p. 4668-4673
ISSN
0027-8424
1091-6490
ISI
000301712600064
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
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.
Full text (open access)
https://repository.uantwerpen.be/docman/irua/9f649b/735287c7.pdf
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