By comparing the genome of the mutant plants with normal plants, the group found a gene that was missing from the mutants. Suspecting that gene might be the culprit, the researchers took a functional version of the gene from normal plants and put it into the mutants. The mutant legumes then began fixing nitrogen the same as normal ones, "proving that we found the right gene," said Wang.
How less is more
Since 1960, the use of nitrogen fertilizer in the United States has roughly quadrupled, as has the price per ton, according to the U.S. Department of Agriculture. Prices have been driven up by the rising cost of natural gas used to manufacture the fertilizer.
"That might make things more expensive for American farmers and increase food prices for consumers, but this is going to wipe out people in developing countries, whose soils are perhaps most in need of fertilizers," Long said. "This is a crucial issue. And nitrogen fixation is a key to sustainability."
Costs aside, the production of chemical fertilizer also adds to the problem of global warming, both by way of the fossil fuels used in production of chemical fertilizer and through the impact of leftover fertilizer that degrades into nitrous oxide, a highly potent greenhouse gas.
With the planet's ever-growing population, Long said there is going to be increased need to keep productivity going on lands that are starting to become marginal because of drought, temperature or salinity problems, among others.
"The rhizobium bacteria are a critical partner in whether that kind of extension of serviceable land can occur," she said. "In order for us to take existing symbioses an
|Contact: Louis Bergeron|