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EXPERIMENT INFORMATION

Molecular Biology of Plant Development in the Space Flight Environment (CARA) (KSC00XX04)
Principal Investigator
Research Area:
Plant biology
Species Studied
Scientific Name: Arabidopsis thaliana Species: Mouse-ear cress Strain: Columbia-0
Scientific Name: Arabidopsis thaliana Species: Mouse-ear cress Strain: WS type
Scientific Name: Arabidopsis thaliana Species: Mouse-ear cress Strain: PhyD

Description
OBJECTIVE:
The space flight environment addresses key gravity-related biological issues using a simple, robust operational approach that has been successfully demonstrated with previous Space Shuttle and International Space Station (ISS) flights. Plants experiencing space flight mount an adaptive response that can be measured in terms of patterns of gene expression and morphological (shape) changes in growth and development. During previous space flight experiments a remarkable number of gene expression changes during space flight that are associated with cell wall restructuring and altered root growth were observed. Differences in the way two distinct ecotypes (genetically distinct population) of Arabidopsis responded to the space flight environment, particularly with respect to inherent root-growth patterns were also observed. This project is designed to tie these observations together.

The Characterizing Arabidopsis Root Attractions (CARA) experiment looks at mechanisms at the molecular and genetic level that influence the growth of a plant’s roots in the absence of gravity, and how those change with or without light. Researchers expose one set of seedlings to light, keep another set in the dark, and then examine how each environment influences the patterns of root growth. Some of the plants are also imaged with the Light Microscopy Module on orbit, and at the end of the experiment, all plants are harvested by the astronaut, and preserved for their return to Earth in order to evaluate genes associated with plant responses on orbit.

Characterizing Arabidopsis Root Attractions (CARA) advances the fundamental understanding of the molecular biological responses to extraterrestrial environments. This understanding further defines the impacts of space flight on biological systems to better enable the United States’ future space exploration goals.

The hypothesis to be tested is that the differences between the WS and Col-0 will reveal key genes involved in the morphology of root growth on orbit. Further, it is hypothesized that phyD contributes to the light-mediated signal transduction that influences the tropic direction of root growth on orbit, and that Col-0 plants deficient in this gene will mimic the negatively phototrophic patterns of WS roots on orbit. Two tools are used for analyses: whole genome transcriptome analyses and morphometric analysis. The results anticipated include the identification of a number of differentially expressed genes that help define gravity-independent responses unique to each ecotype, and insight into the role of the phyD gene in root growth. The fundamental scientific relevance of this experiment is that it provides insight into the signal transduction pathways that control tropism and adaptive physiology in plants. The experiment also showcases how the unique research environment of the ISS provides insight into fundamental and widely applicable biological questions that cannot be answered on earth where gravity would mask many of the underlying phenomena.


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Publications
Genetic dissection of the Arabidopsis spaceflight transcriptome: Are some responses dispensable for the physiological adaptation of plants to spaceflight? pubmed.gov [DOI]

The effect of spaceflight on the gravity-sensing auxin gradient of roots: GFP reporter gene microscopy on orbit. [DOI]

Keywords
Gene expression
Gene expression regulation
Gene expression regulation, plant
Genes, plant
Growth and development
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Data Information
Data Availability
Archive is complete. All data sets are on the Web site.
Data Sets + View data.

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
SpaceX_3 04/18/2014 05/18/2014 30 days

Additional Information
Co-Investigators
Managing NASA Center
PREPHASE1 ( )
Responsible NASA Representative
Institutional Support
Center for the Advancement of Science in Space (CASIS)
Proposal Date
03/01/14