Apple seeds

The tomato seeds that rode the shuttle were developed by Dr. Mariya Khodakovskaya, a post-doctoral researcher in the laboratory of Dr. Heike Sederoff, assistant professor of plant biology.

Sederoff studies how plants respond to gravity. The tomatoes that went into space were altered genetically so that they have less of a substance called inositol triphosphate, or IP3. Brown described IP3 as "an important signaling molecule in the gravity response" of plants.

In effect, IP3 helps tell the plant which way is up so that its roots can grow down. The transgenic tomatoes have less IP3, so their gravity response should be less robust than normal tomatoes. Couple that with free fall, or microgravity conditions in space, and there could be some interesting results. IP3 may also affect drought tolerance, Brown added. The transgenic tomatoes are extremely drought tolerant, their leaves are thicker than normal, and the tomatoes contain more lycopene, an antioxidant.

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The tomatoes that were sent into space are a miniature variety called Micro-Tom, Sederoff said. The plants produce tomatoes the size of a quarter or smaller. Sederoff said four different lines of Micro-Tom tomatoes were sent into space: a wild-type line, two lines that were genetically transformed to produce less IP3 and a fourth control line that was genetically altered, but the alteration does not affect IP3 production.

Sederoff said the plants would be allowed to grow for about six weeks, and then another batch would be planted.

She added that genetic transformation of tomatoes to produce less IP3 is a continuation of work begun by Dr. Wendy Boss, William Neal Reynolds Professor of plant biology, and Dr. Imara Perera, senior researcher in plant biology, several years ago. Perera transformed Arabidopsis plants to alter IP3 production.

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On Earth, plants respond to gravity; the roots automatically grow downward. In the minimal gravity of space, there effectively is no down. So if astronauts are to take plants into space with them, it is imperative that scientists understand how plants respond to gravity.

And if scientists understand how plants respond to gravity, it may be possible to alter them genetically so they are better adapted to life in space. That is what the researchers are working to do. CALS has had a strong space biology program since 1996, when a NASA Specialized Center of Research and Training in Gravitational Biology in Plant Gravitational Biology and Genomics was located in the College.