Plants use 'sixth sense' to grow on ISS

April 2, 2015

These culture dishes hold seedlings and the growing medium for the Plant Gravity Sensing investigation, which were used during astronaut training at the Japan Aerospace Exploration Agencys Tsukuba Space Center in March 2014. (Credit: European Space Agency/S. Corvaja)

Provided by Laura Niles,International Space Station Program Science Office and Public Affairs Office

Although it is arguable as to whether plants have all five human senses sight, scent, hearing, taste and touch they do have a unique sense of gravity, which is being tested in space. Researchers with theJapan Aerospace Exploration Agency will conduct a second run of thePlant Gravity Sensing study after new supplies are delivered by the sixthSpaceX commercial resupply mission to theInternational Space Station. The research team seeks to determine how plants sense their growth direction without gravity. The study results may have implications for higher crop yield in farming and for cultivating plants for long-duration space missions.

The investigation examines the cellular process of formation in thale cress, orArabidopsis thaliana, a small flowering plant related to cabbage. The genetic makeup of thale cress is simple and well-understood by the plant biology community. This knowledge allows scientists to easily recognize changes that occur as a result of microgravity adaptation.

NASA Astronaut Karen Nyberg harvests plants from a Japan Aerospace Exploration Agency investigation of Arabidopsis thaliana during Expedition 37. (Credit: NASA)

Understanding the cellular processes in plant development may translate to better knowledge of cellular processes in the human body. Since thale cress is considered amodel organism for biological research, there are genetic similarities that may reveal insights into our health. Specifically, this could impact medical science since research teams may gain a better understanding of mechanisms of diseases affected by gravity, such as osteoporosis and muscle loss.

In the Plant Gravity Sensing study, scientists examine whether the mechanisms of the plant that determine its growth direction the gravity sensor form in the absence of gravity. Specifically, the research team analyzes how concentrations of calcium behave in the cells of plants originally grown in microgravity when later exposed to a 1g environment, or gravity similar to that on Earth. Plant calcium concentrations have been shown to change in response to temperature and touch and adapt to the direction of gravity on Earth.

Plants cultivated in space are not experienced with gravity or the direction of gravity and may not be able to form gravity sensors that respond to the specific direction of gravity changes, said Hitoshi Tatsumi, Ph.D., principal investigator of the Plant Gravity Sensing investigation and associate professor at Nagoya University in Nagoya (present address: Kanazawa Institute of Technology), Japan.

Researchers use a centrifuge in theCell Biology Experiment Facility inKibo, the Japanese Experiment Module, to monitor the plants response to changes between microgravity and a simulated 1g condition. The research team does this to determine if the plants sense changes in gravitational acceleration and adapt the levels of calcium in their cells.

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Plants use 'sixth sense' to grow on ISS