Plants play an important role in future planning for long-term space missions as they serve as a source of food and generate breathable air for crewmembers. Seedling Growth-1 focuses on the effects of gravity and light on plant growth, development, and cell division. In the long-term, this research is relevant to improving the characteristics of crop plants to benefit human agriculture on Earth.Principal Investigator(s)
Ames Research Center, Moffett Field, CA, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Science Mission Directorate (SMD)ISS Expedition Duration
September 2012 - March 2013
33/34Previous ISS Missions
This experiment builds on previous spaceflight experiments for both Principal Investigators using the model plant Arabidopsis thaliana. In the TROPI (Kiss) experiment in the EMCS on the ISS, data were obtained on the phytochrome photoreceptors responsible for the phototropic response of seedlings grown in microgravity. Growth, development, and phototropic curvature of plants in response to varying qualities of light were analyzed, as well as global gene expression changes using DNA microarrays. In the ROOT experiment (Medina, ISS) and in the experiments GENARA and ROOT CELL PROLIFERATION (approached until now in ground-based facilities), results indicated that cell growth and proliferation in root meristems were altered by changing the effective gravity, including the expression of relevant cell cycle genes. Furthermore, the distribution of auxin was altered, resulting in modifications of the pattern of primary and secondary root growth.
For future exploration initiatives it is vital to use plants in bioregenerative life support systems that rely on plants or other living things to help provide clean air, water, and food for crews. In order to properly design these future systems, improved knowledge of basic plant life mechanisms is very important. Seedling Growth-1 aims to determine the effects of gravity on the signaling mechanism of how plants respond to light, and how those conditions affect plant growth and proliferation.
This experiment builds on previous space flight experiences using the model plant Arabidopsis thaliana. In previous experiments, data was obtained on the photoreceptors responsible for the plant seedlings growing in the direction of the light source when grown in microgravity. Additionally, the growth, development, and the light sensing curvature of plants in the response to varying qualities of light were analyzed. It is thought that red light sensing, known in more primitive plant phyla, is masked by normal Earth gravity (1g) conditions in higher plants. It is also proposed to investigate the fundamental interactions between red and blue light signal pathways, and how they are affected by gravity. Those signal pathways are vital to the regulation of cell growth and proliferation.
Seedling Growth-1focuses on the signal transduction phase, or how the plant cells react to light. Further, the interaction between the red and blue light signaling pathways is investigated by using mutants with modified auxin hormone characteristics in the sensing pathways. The contribution of the light stimuli to the regulation of cell growth, and proliferation, is evaluated by further analysis.
Additionally, with the use of the European Modular Cultivation System (EMCS), it is possible to compare how the light receptors of the plants are influenced by fractional gravity, as the EMCS has a variable speed centrifuge that simulates the reduced or fractional gravity levels that can be found on the Moon and Mars.
The major focus of this project is to determine how gravity and light responses influence each other in plants, and to better understand the cellular signaling mechanisms involved in how plants react to light. Additionally, using the European Modular Cultivation System, it is possible to study plant growth and development at fractional gravity levels as would be seen on the Moon or Mars. Improving the knowledge base of these basic processes is important as ways are developed to use plants in future bioregenerative life support systems for future manned missions.Earth Applications
Light and gravity sensing are key parameters in plant growth and development. Further understanding of how plants are affected by these factors helps in the development of strategies to optimize light sensing in plants, and modifying plant species by using biotechnological approaches to improve crop plants. Improvements in agricultural biotechnology lead to increased crop production, lessened environmental impact, and a greater sustainability of agricultural production to benefit human agriculture on Earth.
For launch, EC's should be oriented in a configuration such that launch loads are directed perpendicular to the base plate. In order to perform the experiment runs, a functional EMCS is required. During the experiment runs while on orbit, images of the experiment in progress are automatically downlinked. Once the experiment has been concluded, the Seed Cassettes are stored frozen, and the ECs are stored at ambient for return to earth.Operational Protocols
The Crew installs ECs into the EMCS for run #1. The Crew and Ground control in N-USOC, Norway will initiate the experiment. At the conclusion of run #1, the Crew will remove the ECs from the EMCS. Crew will then remove the Seed Cassettes, and place them in EMCS Cold Storage Bags, and then place in MELFI. The Crew will then install new ECs in EMCS for experiment run #2. At the conclusion of the run #2, again the Crew will remove the ECs from the ECMS, remove the Seed Cassettes, and place the Seed Cassettes in the EMCS Cold Storage Bags and freeze in MELFI. This process is repeated for runs 3 & 4. The Crew will then place the used EC in ambient storage for return to Earth, while the frozen seed cassettes will be placed in GLACIER for return to earth.