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How Plants Survived Chernobyl

15 May 2009 (All day)
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Ben Fairless; (inset) Namik Rashydov of the National Academy of Sciences of Ukraine

Soy survivor. A soy plant grows in a contaminated field near Chernobyl.

You might expect the scene of the world's worst nuclear disaster to be a barren wasteland. But trees, bushes, and vines overtake abandoned streets surrounding the Chernobyl nuclear power facility in the Ukraine. Now, researchers say they've discovered changes in the proteins of soybeans grown near Chernobyl that could explain how plants survive despite chronic radiation exposure. The findings could one day help researchers engineer radiation-resistant crops.

In April 1986, a reactor at the Chernobyl plant exploded, sending clouds of radioactive material across the countryside. Some radioactive substances with decades-long half-lives, such as cesium-137, persist to this day. Studies have shown deformities in local wildlife, and the 30-kilometer radius around the former plant is officially off-limits, though a few hundred elderly citizens still eke out an existence there. Despite the devastation, local flora flourishes. "You would never guess something happened there 23 years ago," says Martin Hajduch, a plant biologist at the Slovak Academy of Sciences in Nitra.

Hajduch and colleagues wanted to find out how these postnuclear plants survive. The team planted soybeans inside the 30-kilometer restricted zone, just 5 kilometers from the remains of the power plant. They then planted an identical batch of soybeans 100 kilometers from the plant, where cesium-137 levels were 163 times lower. After several months, the researchers harvested mature beans from the plants and analyzed the proteins inside.

The radiation zone beans looked odd even before the protein analysis. They weighed half as much and took up water more slowly than their low-radiation counterparts. And on a molecular level, the beans were even stranger, the researchers report in the June Journal of Proteome Research. When compared with normal plants, beans from the high-radiation area had three times more cysteine synthase, a protein known to protect plants by binding heavy metals. They also had 32% more betaine aldehyde dehydrogenase, a compound found to reduce chromosomal abnormalities in human blood exposed to radiation. Seed storage proteins, which provide nitrogen for germinating seeds, also showed up in different concentrations--some higher, some lower--than in regular soy.

So what do the researchers make of this molecular milieu? The plants seem to be protecting themselves from Chernobyl's low-level radiation, says Hajduch, but no one knows how these protein changes translate into survival, or if they'll be passed on to the plants' offspring. The team plans to analyze four generations of beans to investigate further.

The research "really is novel and addresses an important societal question, especially given the growing interest in developing nuclear energy worldwide," says Timothy Mousseau, a biologist at the University of South Carolina in Columbia who studies Chernobyl-area wildlife. If researchers can understand how plants respond to radiation, Mousseau says, they could begin to engineer crops to withstand--or even sequester and remove--nuclear contamination.

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