The Plant Signaling experiment studies the effects of microgravity on the growth of plants. The experiment is performed on board the International Space Station (ISS) in collaboration with the European Space Agency (ESA). Images of the plants are captured and down-linked to Earth. Samples of the plants are harvested and returned to Earth for scientific analysis. The results of this experiment can lead to information that will aid in food production during future long duration space missions, as well as data to enhance crop production on Earth.Principal Investigator(s)
NASA Ames Research Center, Moffett Field, CA, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)Research Benefits
Information PendingISS Expedition Duration
March 2011 - September 2011Expeditions Assigned
27/28Previous ISS Missions
Increment 27/28 is the first planned increment for the Plant Signaling investigation.
The investigator?s primary aim of the Plant Signaling investigation is to identify the molecular changes that are specifically mediated by InsP3 in the space environment. The investigators compare transcript and protein profiles of wild type and transgenic plants that are grown in both microgravity and 1g in space, as well as on the ground. The long term goal of Plant Signaling is to understand the molecular mechanisms plants use to sense and respond to changes in their environment. This knowledge will help design plants that are better able to withstand space flight and microgravity conditions. The Plant Signaling experiment will utilize the European Space Agency?s European Modular Cultivation System (EMCS) located on board the International Space Station in the Columbus Module.
Plants provide a complete and economical means for human life support for long-duration space exploration and habitation. However, since the space environment is not optimal for plant growth, an understanding of how plants sense and respond to changes in their environment is of fundamental importance. The phosphoinositide (PI) pathway (responsible for the regulation of a wide variety of cellular processes) is found in all eukaryotes (organisms with cells with a nucleus) and functions in the regulation of a multitude of cellular pathways. The lipid-derived second messenger, inositol 1,4,5-trisphosphate (InsP3) (an intracellular signaling molecule), increases in response to many different stresses; such as drought, water, salt and cold.
As part of the Plant Signaling investigation, the PI has shown that InsP3 levels increase with gravistimulation prior to visible bending in both monocot and dicot systems. The PI has generated transgenic Arabidopsis (small flowering plants which contain a gene or genes that have been artificially inserted into the plant instead of the plant acquiring the gene(s) through pollination) plants expressing the mammalian Type I inositol polyphosphate 5-phosphatase (InsP 5-ptase), an enzyme that specifically hydrolyzes InsP3 and terminates the signal. The transgenic plants have normal growth and morphology; however, they exhibit altered responses to many environmental stimuli including gravity, drought and cold. While rapid changes in transcript levels occur in wild type Arabidopsis within five minutes of gravistimulation, the expression of several of the fastest responding genes does not change in the InsP 5-ptase roots in response to reorientation.
The experiment hypothesis is that InsP3 is an important second messenger in the sensing and signaling of stimuli (including gravity). The plants with compromised InsP3 signaling therefore provide a valuable tool for dissecting the role of the InsP3 pathway in plant responses to the microgravity environment encountered on the International Space Station (ISS).
During long-duration space missions, it will be necessary to provide crewmembers with regenerative sources of food as well as supplemental methods to recycle carbon dioxide into breathable oxygen. As new information about how plants grow in microgravity emerges, sustainable plant-based life support systems may be developed.Earth Applications
Further understanding of how plants grow and develop at a molecular level can lead to significant advancements in agricultural production on Earth. Understanding mechanisms of plant development will support improved agricultural production and lead to higher crop yields on Earth.
16 EC/EUE/Seed Cassettes are required to be delivered to the ISS on 44P. For launch, the ECs will be oriented such that launch loads are directed perpendicular to the baseplate. At selected times, the images will be automatically downlinked. The EMCS facility is required to perform experiment runs. The MELFI facility is required to store the frozen samples. An active temperature control device is required for containing frozen samples and maintaining temperature for return to Earth.Operational Protocols
Experiment Containers (ECs) containing Seed Cassettes will be transported from ambient storage and installed in the EMCS facility. ESA N-USOC Ground Operations Center will initiate automated sequence for hydration, atmospheric control, image capture, lighting, and centrifuge speed (g-level). Automated image capture is obtained according to the experiment timeline. At the conclusion of the automated experimental sequence, ECs will be removed from the EMCS Facility and Seed Cassettes will be removed from the ECs. Seed Cassettes are to be placed in EMCS Cold Bags and stowed in MELFI until returned to Earth. ECs will be placed in ambient stowage until returned to Earth. For return to Earth, Seed Cassettes will be placed in active cold stowage (Glacier), and ECs should be placed in ambient stowage.
Perera IY, Hung C, Brady S, Muday GK, Boss WF. A universal role for inositol 1,4,5-trisphosphate-mediated signaling in plant gravitropism. Plant Physiology. 2006; 140: 746-760.
Perera IY, Heilmann I, Chang SC, Boss WF, Kaufman PB. A role for inositol 1,4,5-trisphosphate in gravitropic signaling and the retention of cold-perceived gravistimulation of oat shoot pulvini. Plant Physiology. 2001; 125: 1499-1507.
Perera IY, Heilmann I, Boss WF. Transient and sustained increases in inositol 1,4,5-trisphosphate precede the differential growth response in gravistimulated maize pulvini. Proceedings of the National Academy of Sciences of the United States of America. 1999; 96(10): 5838-5843.
Perera IY, Hung C, Moore CD, Stevenson-Paulik J, Boss WF. Transgenic Arabidopsis plants expressing the Type 1 inositol 5-phosphatase exhibit increased drought tolerance and altered abscisic acid signaling. The Plant Cell. 2008; 20: 2876-2893.