Shoot gravitropism and organ straightening cooperate to arrive at a mechanically favorable shape in Arabidopsis

Gravitropism is the plant organ bending in response to gravity, while a straightening mechanism prevents bending beyond the gravitropic set-point angle. The promotion and prevention of bending occur simultaneously around the inflorescence stem tip. How these two opposing forces work together and wha...

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Published in:Scientific reports 2023-07, Vol.13 (1), p.11165-11165, Article 11165
Main Authors: Tsugawa, Satoru, Miyake, Yuzuki, Okamoto, Keishi, Toyota, Masatsugu, Yagi, Hiroki, Terao Morita, Miyo, Hara-Nishimura, Ikuko, Demura, Taku, Ueda, Haruko
Format: Article
Language:English
Subjects:
631/449/1975
631/57/2266
639/705
Arabidopsis
Biology
Deficient mutant
Finite element method
Gravitropism
Humanities and Social Sciences
Life sciences
Mathematical models
multidisciplinary
Myosin
Prevention
Proprioception
Science
Science (multidisciplinary)
Signal transduction
Stems
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Summary:Gravitropism is the plant organ bending in response to gravity, while a straightening mechanism prevents bending beyond the gravitropic set-point angle. The promotion and prevention of bending occur simultaneously around the inflorescence stem tip. How these two opposing forces work together and what part of the stem they affect are unknown. To understand the mechanical forces involved, we rotated wild type and organ-straightening-deficient mutant ( myosin xif xik ) Arabidopsis plants to a horizontal position to initiate bending. The mutant stems started to bend before the wild-type stems, which led us to hypothesize that the force preventing bending was weaker in mutant. We modeled the wild-type and mutant stems as elastic rods, and evaluated two parameters: an organ-angle-dependent gravitropic-responsive parameter ( β ) and an organ-curvature-dependent proprioceptive-responsive parameter ( γ ). Our model showed that these two parameters were lower in mutant than in wild type, implying that, unexpectedly, both promotion and prevention of bending are weak in mutant. Subsequently, finite element method simulations revealed that the compressive stress in the middle of the stem was significantly lower in wild type than in mutant. The results of this study show that myosin-XIk-and-XIf-dependent organ straightening adjusts the stress distribution to achieve a mechanically favorable shape.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-023-38069-x