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Drought tolerance is next step in crop traits
It's not your dad's corn hybrid anymore.
Despite hot and dry conditions this summer, corn yields across the U.S. in 2006 will average 153.5 bushels/acre. Those high yields are due, in part, to superior genetics.
Plant Science companies want to see even higher corn yields in the near future.
Syngenta Seeds, Inc., of Golden Valley, Minn., is studying a number of traits that could make corn more tolerant to hot and dry conditions. They hope to be the first company to offer corn with built-in drought tolerance.
Two scientists are overseeing Syngenta's work in drought tolerance.
Scott Valentine, at Syngenta Biotechnology in North Carolina, is leading the development of the company's biotech trait for drought tolerance. John Arbuckle, at Syngenta in Stanton, Minn., is leading the company's native traits program.
While Valentine's team is researching gene technology from donor plants, Arbuckle's team is looking at genes within corn plants that have some level of drought tolerance.
“Some people may be under the impression that our program of native traits marker-assisted precision breeding is somehow supplanting genetic modification approaches. We don't really view it that way,” said Arbuckle. “We view them as parallel approaches that can actually benefit each other.”
Historically, perhaps 90 percent of the gains in corn hybrids have come from classical or conventional plant breeding. The breeder selects plants that display positive traits to develop hybrids.
We've also experienced the first wave of biotechnology traits. From Syngenta, these products have included the use of Bacillus Thuringiensis (Bt) to control European corn borer.
Other products offer glyphosate tolerance, Liberty herbicide tolerance, and corn rootworm control with Syngenta's Agrisure RW product line.
Now working on the second wave of biotechnology traits - such as drought tolerance - is challenging.
That's because the corn plant didn't need to recognize the Bt gene. Bt is a toxin that remains inert within the corn plant.
Working with drought tolerance is different.
“What we are doing now is changing the corn plant's biochemistry and its pathways,” said Valentine. “The second generation of agronomic traits more closely affect the performance of the plant and really affect yield.”
Scientists have a number of thoughts on how to increase drought tolerance in corn.
Syngenta is working with Performance Plants, Inc. - a Kingston, Ontario, Canada company that has found a way to make the corn plant hold its moisture.
Performance Plants calls their biotechnology event Yield Protection Technology. The technology protects crops exposed to drought conditions by stimulating early closure of the leaf stomata prior to wilting.
Stomata are the openings on leaves that allow for transpiration or the exchange of gases. There is water loss through these openings, Valentine said.
“When you tighten those pores, you can retain more water,” he said. “That could help plants under low water conditions to retain their water.”
Valentine pointed out that the plants still need open stomata to complete photosynthesis and allow the exchange of carbon dioxide and oxygen. In normal situations, though, leaf pores close during high heat and stress anyway. That's why you don't spray crop chemicals when it's very hot or in the middle of the day. Syngenta wants to determine the impact to yield from closing those pores sooner.
Four years of field research from Performance Plants have shown favorable results.
Valentine says there is no timetable yet for commercialization of the Yield Protection Technology trait in corn.
Arbuckle's Syngenta team is looking at drought tolerance already located within the corn plant. These corn plants come from all around the world - as well as from the Midwest.
“There's a lot of genetic diversity that resides with the corn that farmers use here in the Midwest,” said Arbuckle. “One of our objectives is to understand that and combine the best genes to deliver the traits that farmers want.”
Arbuckle is trying to find those corn plants that have strong drought tolerance as well as good production traits.
Then the Syngenta team uses genomics technologies, high-throughput genotyping, precision phenotyping, geographic information systems science and computational biology tools to develop molecular markers for drought tolerance.
“It's smart breeding to determine genetic markers,” said Valentine, speaking of Arbuckle's program. “It's really conventional breeding with more expensive tools. It's also faster and you really focus on exactly what you're going after. You're not going after a phenotype - you're going after a genomic sequence.”
At this time, Arbuckle's research has associated many genes with drought tolerance in corn. Syngenta breeders are then using precision breeding to assemble the most promising genes into hybrids.
But simply putting drought tolerance successfully into a hybrid won't be enough.
“We are not going to sacrifice any good trait to bring drought tolerance,” said Arbuckle. “Drought tolerance has to be part of the total hybrid package.”
“When drought tolerance comes to the market in the form of hybrids, it won't have yield drag,” said Valentine. “We won't push something to the market that we know has problems.”
Syngenta officials say there are a number of reasons to focus on drought tolerance.
With drought tolerance in corn, farmers should be able to grow significant yields under less than normal moisture conditions.
Bt technology preserves the potential yield, but drought tolerance would increase yields that would otherwise be lost under stressful conditions.
Syngenta also hopes the trait will allow growers to raise more corn using less irrigation - a significant concern throughout the United States.
The trait could also give farmers the opportunity to convert marginal farmland into productive cropland.
Currently, the corn industry expects to need 5-7 million more acres of harvested corn in 2007 to keep up with ethanol production, domestic use, and U.S. export markets.
Providing commercially viable drought tolerant corn hybrids could be part of the answer to finding needed corn supplies with a shrinking cropland base across the United States.
