Cucumbers in space

Scientists at Tohoku University in Japan have untangled the competing influences of water and gravity on plant roots – by growing cucumbers in spaceflight.

Plant roots grow to find water – a process called hydrotropism. Roots are also influenced by gravity and tend to grow downwards – this is called gravitropism.

Studying the effect of hydrotropism on roots on Earth is difficult because of the competing influence of gravitropism. To find out whether gravity or water had the greater influence on root growth, the scientists grew cucumber plants in the microgravity environment on board the International Space Station.

Image: Astronaut Dr Jon Garan watering cucumber seedlings on board the ISS. Credit JAXA, NASA.
Astronaut Dr Jon Garan watering cucumber seedlings on board the ISS. Credit JAXA, NASA.

In their experiments, the scientists were able to untangle the competing effects of water and gravity to show that, in microgravity, water (hydrotropism) had more influence in controlling root growth.

“We will be able to utilise roots’ ability to sense moisture gradients for controlling root growth orientation and efficiently growing plants in future space farms,” said Dr. Hideyuki Takahashi, senior author of the study, published in New Phytologist.

Read the paper:

Morohashi, K., Okamoto, M., Yamazaki, C., Fujii, N., Miyazawa, Y., Kamada, M., Kasahara, H., Osada, I., Shimazu, T., Fusejima, Y., Higashibata, A., Yamazaki, T., Ishioka, N., Kobayashi, A. and Takahashi, H. (2017) Gravitropism interferes with hydrotropism via counteracting auxin dynamics in cucumber roots: clinorotation and spaceflight experiments. New Phytologist. doi: 10.1111/nph.14689

Read the press release.

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Mike Whitfield
Development Coordinator
New Phytologist

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