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We're being reminded, again, this year how much we all depend on rain. A drought last summer in Russia has pushed wheat prices to their highest levels in years. Scientists are searching for ways to make wheat less vulnerable to drought, and they're exploring some novel approaches. Paradoxically, some are trying to replace the genes that made possible the dramatic boost in wheat harvests known as the Green Revolution. NPR's Dan Charles has the story.

DAN CHARLES: Few people can see the accomplishments of the Green Revolution more clearly than Kulvinder Gill. First of all, he grew up in a village in India where half a century ago some predicted catastrophe because food production wasn't growing as fast as the population.

Mr. KULVINDER GILL: It was a common belief that this world is going to end because of the starvation. People are going to fight for food and kill each other.

CHARLES: But scientists such as Orville Vogel at Washington State University bred new varieties of wheat that included a mutant gene that kept the plant short. When you gave these plants lots of fertilizer and irrigated them, they didn't just get tall and fall over like ordinary wheat, they produced more grain - a lot more.

Mr. GILL: These dwarfing genes came and almost tripled yield, at least in Punjab area.

CHARLES: Kulvinder Gill left his village in Punjab and became a wheat geneticist. He now occupies the Orville Vogel Endowed Chair in Wheat Breeding at Washington State. And he's hoping to repeat what Vogel did, but improve on it. Because the dwarfing genes of the green revolution - which are now in 90 percent of all the wheat that farmers grow around the world - have an unfortunate side effect, he says. They make it harder for the plant to thrive when water is scarce. For instance, when it's dry, farmers have to plant seeds deeper because that's where the moisture is.

Mr. GILL: And these semi-dwarfs don't do too good, pushing out of six inches of soil.

CHARLES: Gill is now on the hunt for a different, and better dwarfing gene. He knows exactly what he's looking for. It's a mutation that already exists in corn and sorghum. It doesn't shrink the whole plant the way the green revolution genes do, instead, it blocks the normal flow of a crucial growth hormone.

Mr. GILL: So the plant reduces in height, but at the same time the cob is bigger, the stem is thicker and stronger. And this plant looks just great.

CHARLES: To create this kind of wheat plant, Gill and a group of collaborators have treated thousands of seeds with a chemical that makes random changes in DNA. Now these mutant wheat plants are growing in the greenhouse. And Gill has to see if any of them have the one change he wants.

Mr. GILL: It is very difficult to know, at this point, if the mutant is the one - the kind we are looking for.

CHARLES: Gill's project is just one part of a global campaign to reprogram crops genetically so they can survive water shortages. People are trying everything from low-tech traditional crop breeding to high-tech gene splicing. One approach somewhere in the middle, involves looking for useful genes in wheat's ancestors. Scientists are retrieving seeds from the refrigerated vaults of so-called gene banks, taking a fresh look at those plants. Thousands of years ago, three of them somehow combined in the wild to form modern wheat. David Bonnet, a wheat geneticist at the International Maize and Wheat Improvement Center called CIMMYT based in Mexico, says scientists can re-create that merger in the laboratory.

Mr. DAVID BONNET (Wheat Geneticist, International Maize and Wheat Improvement Center): So we can go back and bring in more genetic variation for a whole range of traits, but certainly drought tolerance has been one of them.

CHARLES: But the approach that's getting most of the attention and most of the money these days, is genetic engineering. The company Monsanto has inserted a gene from bacteria into corn and the company says this variety yields eight to 10 percent more under drought conditions. The gene is called a transcription factor, a kind of master gene that activates many others when the plant is under stress. The company says if it gets a green light from regulators it will start selling the corn within two years.

Monsanto has also donated the gene to a group of government-supported research institutions in Africa. They're starting greenhouse trials of the corn this year.

In the scientific community there's a lot of curiosity about the Monsanto product and some skepticism that it will work as advertised. But lots of people, also, are looking for genes to splice into crops. Mahyco, for instance, a leading seed company in India. Usha Zehr is the company's chief technology officer.

Ms. USHA ZEHR: In our program, we are looking at transcription factors from drought tolerant crops - sorghum, acacia trees, or other plants which are known to be drought tolerant.

CHARLES: David Bonnet at the research center CIMMYT says there's no shortage of genes that seem like they might possibly help a plant use water more efficiently.

Mr. BONNET: We have access to quite a number of candidates ourselves, and we think they have as much or more potential as what Monsanto has.

CHARLES: Actually realizing that potential may become increasingly important as the globe warms up. Climate models predict that many parts of the world, including major crop-growing areas, will see more drought in the coming years.

Dan Charles, NPR news, Washington.

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