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<p>For long-term space missions, it is necessary to understand how organisms respond to changes in gravity. Plant roots are positively gravitropic; the primary root grows parallel to gravity's pull even after being turned away from the direction of gravity. We examined if this gravitropic response varies depending on the time of day reorientation occurs. When plants were reoriented in relation to the gravity vector or placed in simulated microgravity, the magnitude of the root gravitropic response varied depending on the time of day the initial change in gravity occurred. The response was greatest when plants were reoriented at dusk, just before a period of rapid growth, and were minimal just before dawn as the plants entered a period of reduced root growth. We found that this variation in the magnitude of the gravitropic response persisted in constant light (CL) suggesting the variation is circadian-regulated. Gravitropic responses were disrupted in plants with disrupted circadian clocks, including plants overexpressing Circadian-clock Associated 1 (CCA1) and <italic>elf3</italic>-2, in the reorientation assay and on a 2D clinostat. These findings indicate that circadian-regulated pathways modulate the gravitropic responses, thus, highlighting the importance of considering and recording the time of day gravitropic experiments are performed.</p>
</abstract>

For long-term space missions, it is necessary to understand how organisms respond to changes in gravity. Plant roots are positively gravitropic; the primary root grows parallel to gravity's pull even after being turned away from the direction of gravity. We examined if this gravitropic response varies depending on the time of day reorientation occurs. When plants were reoriented in relation to the gravity vector or placed in simulated microgravity, the magnitude of the root gravitropic response varied depending on the time of day the initial change in gravity occurred. The response was greatest when plants were reoriented at dusk, just before a period of rapid growth, and were minimal just before dawn as the plants entered a period of reduced root growth. We found that this variation in the magnitude of the gravitropic response persisted in constant light (CL) suggesting the variation is circadian-regulated. Gravitropic responses were disrupted in plants with disrupted circadian clocks, including plants overexpressing Circadian-clock Associated 1 (CCA1) and elf3-2, in the reorientation assay and on a 2D clinostat. These findings indicate that circadian-regulated pathways modulate the gravitropic responses, thus, highlighting the importance of considering and recording the time of day gravitropic experiments are performed.

The Circadian-clock Regulates the <italic>Arabidopsis</italic> Gravitropic Response

Genetics Program North Carolina State University

Department of Molecular and Structural Biochemistry

North Carolina State University Raleigh NC

Amentum, LASSO, Microgravity Simulation Support Facility, Kennedy Space Center

Department of Plant and Microbial Biology

Gravitational and Space Research

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

The Circadian-clock Regulates the  Gravitropic Response

For long-term space missions, it is necessary to understand how organisms respond to changes in gravity. Plant roots are positively gravitropic; the primary...

The Circadian-clock Regulates the Arabidopsis Gravitropic Response

Article Category: Research Note

Publicado en línea: 31 dic 2021

Páginas: 171 - 186

DOI: https://doi.org/10.2478/gsr-2021-0014

Palabras clave
Gravitropism, circadian rhythms, simulated microgravity

© 2021 Joseph S. Tolsma et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

The Circadian-clock Regulates the Arabidopsis Gravitropic Response

Article Category: Research Note

Publicado en línea: 31 dic 2021

Páginas: 171 - 186

DOI: https://doi.org/10.2478/gsr-2021-0014

Palabras claveGravitropism, circadian rhythms, simulated microgravity

© 2021 Joseph S. Tolsma et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Palabras clave
Gravitropism, circadian rhythms, simulated microgravity