Microgravity may multiply success of gene transfers

Transferring desirable genes into crops is a high-tech game of chance, with success rates running about one in 1,000. But the odds get a whole lot better, it seems, when you remove gravity from the mix.

An industry-sponsored research project aboard the NASA Space Shuttle Discovery last year suggests that microgravity might enhance genetic engineering of plants. The project, coordinated by the Wisconsin Center for Space Automation and Robotics (WCSAR), tested a unique technology that uses bacteria as a means for gene transfer.

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“The level of genetic transfer from infection was way beyond our expectations,” says Ray Bula, the retired director of WCSAR. “We thought if we could double the rate of transfer seen on earth, it would have been promising.”

The increase in genetic transfer was more than 10-fold compared to a control experiment conducted on Earth, Bula says.

Collaborators in the mission include the Indiana Crop Improvement Association (ICIA), the Cross Plains, Wis., biotechnology firm Rapigen LLC and the University of Toledo. Researchers from Toledo developed the gene transfer process and the ICIA is interested in applying the results to new soybean crops.

Bula says the team is excited about the results, but cautioned that the experiment needs to be refined and repeated to ensure that the seedlings survive.

Toledo’s process begins by slightly damaging the meristem region of plant seedlings. Next, a bacteria that carries the gene is placed in a solution around the plant. The bacteria provide the desired gene that is incorporated into the cells.

All subsequent plant parts derived from these cells will carry the desired trait.

Normally, the bacteria simply die off without harming the plant. But the rate of infection was so high in microgravity that it blocked the vascular system of the plants. On future missions, Bula says the problem can be corrected in part by using less bacteria than is needed on earth.

Why are genes behaving differently in space? Bula says cell materials do not settle out in microgravity, which allows more freedom of movement. With a minimum of physical factors to limit the mobility of bacteria, Bula says, they hit their target more easily.

Gene transfer techniques are increasingly important to the agriculture industry, as it looks for faster and more selective alternatives to complement traditional plant breeding. Bula says that this growing season, genetically engineered varieties are expected to make up 70 percent of all soybeans planted nationally.

“We will be growing crops in the future for more than just food, clothing or energy,” says Bula. “Medical vaccines can be incorporated into plants to provide natural protection from disease. Genes that can make plants resistant to insects will greatly reduce chemical pesticide use.”

The gene in this experiment was a marker gene, which is fluorescent and can be easily tracked. In future experiments, Bula says plans are to transfer a gene that has been shown to relieve certain human autoimmune diseases.

All the interest in conducting gene transfer in space is far from an academic exercise. Fully 30 percent of the International Space Station, now being assembled in orbit, is dedicated to private commercial use. Companies involved in plant genetic engineering are potential users of this new facility.