Japanese astronauts are taking cucumbers into space in a major new experiment to understand off-planet plant growth.
We all know that plants are fundamental to life on Earth, not only providing the oxygen we breathe, but the food we eat as well. For long term space missions to be carried out successfully, the astronauts will need to take plants with them. But how will plants respond to the environment of a space station, and in particular, the lack of gravity?
The first study on cucumbers by the Japan Aerospace Exploration Agency (JAXA) looked at directional root growth. They found that, rather than growing downwards, under microgravity the cucumber roots grew sideways.
In the latest study, the team will investigate whether hydrotropism can be used to control the direction of root growth in microgravity.
The NASA website reports that "To perform the HydroTropi experiment, astronauts transport the cucumber seeds from Earth to the space station and then coax them into growth. The seeds, which reside in Hydrotropism chambers, undergo 18 hours of incubation in a Cell Biology Experiment Facility or CBEF. Then the crewmembers activate the seeds with water or a saturated salt solution, followed by a second application of water 4 to 5 hours later. The crew harvests the cucumber seedlings and preserves them using fixation tubes called Kenney Space Center Fixation Tubes or KFTs, which then store in one of the station MELFI freezers to await return to Earth.
The results from HydroTropi, which returns to Earth on STS-133, will help investigators to better understand how plants grow and develop at a molecular level. The experiment will demonstrate a plant’s ability to change growth direction in response to gravity (gravitropism) vs. directional growth in response to water (hydrotropism). By looking at the reaction of the plants to the stimuli and the resulting response of differential auxin -- the compound regulating the growth of plants -- investigators will learn about plants inducible gene expression. In space, investigators hope HydroTropi will show them how to control directional root growth by using the hydrotropism stimulus; this knowledge may also lead to significant advancements in agriculture production on Earth."
