The Plant Signaling experiment studied the effects of microgravity on plant growth. During long-term space exploration it will be necessary to provide astronauts with regenerative sources of food. As new information about how plants grown in microgravity emerges, sustainable plant-based life support systems may be developed.

The Effect of Spaceflight on Transgenic Arabidopsis Plants With Compromised Signaling

Principal Investigator: Dr. Imara Perera, North Carolina State University, Raleigh, North Carolina

Payload Developer: NASA Ames Research Center

Payload Overview
Plant Signaling studied the effects of gravity (0 and 1g) on the biochemical responses of Arabidopsis thaliana plant seedlings (roots and shoots; wild type and genetically modified plants). Images of seedlings were captured and down-linked to Earth during the on-orbit experiment. Plant samples were harvested at the end of the experiment and preserved on orbit for post-flight analysis on Earth.

Left: Astronaut Lopez-Alegria performing EMCS- Experiment Container replace. Center: Astonaut Lopez-Alegria works with EMCS - Experiment Containers. Right: EMCS Experiment Container with ARC EUE/Plant Seedling Seed Cassettes

Arabidopsis Thaliana seedlings in Seed Cassette, day 5, during the ISS on-orbit experiment

The experiment was conducted in the European Space Agency's (ESA) European Modular Cultivation System (EMCS), located on the International Space Station (ISS) in the Columbus Module. Sixteen Experiment Containers (ECs) containing Plant Seedling Seed Cassettes (with Arabidopsis seeds) were launched on Space Shuttle Atlantis and installed by the crew into the EMCS. Personnel on Earth at ESA’s Norwegian User Support Operations Center (N-USOC) initiated an automated software command sequence for hydration of the seeds, atmospheric control, image capture, lighting, and centrifuge speed (g-level). Automated image capture was performed according to the experiment timeline. At the conclusion of the experiment, ECs were removed from the EMCS Facility and the Seed Cassettes were removed from the ECs. Seed Cassettes were placed in EMCS Cold Bags and stowed in the Minus Eighty Degree Laboratory Freezer on the ISS (MELFI), where they remain until they are returned to Earth. The empty ECs are in ambient stowage on ISS until they are returned to Earth for refurbishment.

It is planned that the ECs will return at ambient on the SpaceX Demo flight in 2012. The scientifically-vital frozen cassette samples are manifested for return on SpaceX-1 in August 2012. For this return flight, the samples will be transferred to the General Laboratory Active Cryogenic ISS Experiment Refrigerator (GLACIER) in the SpaceX Dragon capsule which will maintain them at -80°C.

While this project addresses basic research questions in plant biology, the research will also provide insights into the cultivation of plants during spaceflight on long-term missions. Ultimately, understanding mechanisms of plant development will aid in improving crop production and agricultural yields on Earth.

Launched: July 8, 2011, Final Shuttle Flight
Orbiter: Atlantis
Orbiter Mission Number: STS-135
Increment: Ascent on STS-135 Increment 28; operation Increment 29-30; descent on SpaceX-Demo (ECs) and SpaceX-1 (Frozen samples)

Members of the ARC Plant Signaling Team