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Actin Regulation of Arabidopsis Root Growth and Orientation During Spaceflight (NNX10AF43G)
Principal Investigator
Research Area:
Plant biology
Species Studied
Scientific Name: Arabidopsis thaliana Species: Mouse-ear cress Strain: Col-0

We conducted experiments utilizing the Biological Research in Canisters (BRIC)- Petri Dish Fixation Unit (PDFU) onboard STS-131 to understand how the actin cytoskeleton dictates root growth orientation during spaceflight. Our guiding hypothesis was that actin filaments (F-actin) negatively regulate environmental and endogenous signals to specify root orientation on earth and in space. This hypothesis was based on previous NASA-funded ground based research (grant NAG2-1518) demonstrating that F-actin disruption enhanced the sensitivity of roots to gravity. We utilized Arabidopsis seedlings with a transfer (T)-DNA mutation in a vegetative actin isoform (act2) and the short-duration microgravity environment provided by the STS-131 mission to test our hypothesis. Microgravity was an essential component of our proposed experiments because it allowed us to determine the impact of other environmental signals on root orientation that are typically masked by the strong gravitational force on earth. Using two unpowered BRIC units, we quantified root orientation of dark-grown act2 and wild-type seedlings (aim 1). In parallel, we conducted an extensive set of genome-wide microarray studies using Affymetrix ATH1 arrays to unravel actin-dependent gene regulatory networks that modulate root growth and orientation during spaceflight (aim 2). Although such experiments required minimal manipulation from the flight crew, we were able to collect a robust dataset that has paved the way for an in depth understanding of plant growth under microgravity, a goal consistent with the overall mission of NASA. Another significant deliverable of our project will be the inclusion of a photo-documentary article that will outline the activities of the selected Arabidopsis BRIC16 proposals in a book that will be published by Gakken Education Publishing Co., Ltd. which is the largest educational publication company in Japan. This will provide NASA with a new venue to highlight the significance of its life sciences space program to the general public. The results of our experiments on STS-131 showed that microgravity triggers the transcriptional reprogramming of genes encoding cell wall-related genes. As a consequence of these changes in gene expression, root growth orientation and root hair tip growth were modified during spaceflight. In addition to providing a deeper understanding to microgravity effects on plant development, results from this spaceflight proposal have uncovered new molecular players that regulate root development.

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Data Information
Data Availability
Archive is complete. No data sets are available for this experiment. Please Contact LSDA if you know of available data for this investigation.

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
STS-131 04/05/2010 04/20/2010 15 days

Additional Information
Managing NASA Center
Kennedy Space Center (KSC)
Responsible NASA Representative
Kennedy Space Center LSDA Level 3
Project Manager: Martha Del Alto
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source
2009 Space Life Sciences-