Beyond Roundup Ready: Genetics will address other crop challenges in the future
Nebraska farmers have shown a willingness to plant genetically modified crops to gain the upper hand against weeds. Within a few years, a University of Nebraska-Lincoln weed scientist predicts, seed companies will respond with new crops designed to work with a broader range of herbicides, and eventually the ability to produce a good crop even when water and nitrogen are in limited supply.
Dr. Robert Wilson, weed specialist at the UNL Panhandle Research and Extension Center, said at least 10 million acres of cropland in Nebraska were planted to Roundup Ready crops in 2008, including more than 90 percent of all soybeans, 80 percent of all corn, and 90 percent of all sugarbeets.
Roundup Ready crops, genetically modified to be resistant to Roundup and other glyphosate herbicides, have been available commercially for about 10 years. They include soybeans, corn, canola, cotton, and sugarbeets. These cultivars allow the use of glyphosate to control weeds without hurting the crop.
Roundup Ready sugarbeets comprised 90 percent of the crop's acreage in 2008, and Wilson said they probably will account for 99 percent in 2009. Wilson said most people he's talked to were pleased with their weed control program.
"Farmers like it and that's what they're planting," Wilson said of Roundup Ready seed.
In the future, he said, genetic modifications will be performed on a variety of crops and will address a wide range of challenges faced by farmers. In addition to Roundup, crops will be given resistance to other herbicides with different control modes. Crop genetics will be modified to make the plants more resistant to drought, or better able to utilize residual soil nitrogen, or tolerant of frost. New cultivars will be developed with special suitability for specific uses such as ethanol production.
Seed companies are already beginning to develop new products to stay ahead of weeds that have developed tolerance or resistance to ghyphosate, according to Wilson. In fields of Roundup Ready corn, resistant horseweed (marestail) has been observed in Nebraska. Common ragweed with suspected resistance to ghyphosate has been observed in eastern Nebraska. In western Nebraska, common lambsquarter and toothed spurge seem to be more difficult to control with glyphosate.
Wilson said companies are developing new crops that "double stack" tolerance to glyphosate with a second herbicide. Monsanto is developing corn, soybeans and cotton with tolerance to dicamba (marketed as Clarity, and used to control broadleaf weeds).
Another manufacturer, DuPont, is combining Roundup tolerance and sulfonylurea tolerance. (Sulfonylureas include a whole family of commercial products, such as Basis and Steadfast). These new varieties will be extremely tolerant, so herbicides can be used at planting or after crop emergence, Wilson said.
Dow Chemical Co. identified the gene for 2,4-D tolerance so it can be combined with glyphosate tolerance. This could result in a plant that tolerates three herbicides. Corn is already available with tolerance to both glyphosate and Liberty, because the gene that confers resistance to rootworms also confers tolerance to Liberty (a broad-spectrum herbicide marketed by Bayer). So Dow might produce corn that is tolerant to three herbicides--glyphosate, 2,4-D, and Liberty.
Once crops become available with "double stacked" tolerance, the respective herbicide blends will become available as well, Wilson predicted, in the form of package mixes of glyphosate with the other chemicals.
What about other threats to crops, especially insects and drought?
Wilson said corn already has been developed with one gene that controls root feeding insects and another that controls leaf-feeding insects. The future is likely to bring two different genes for root-feeding insects, and two different genes for leaf feeders. The Environmental Protection Agency currently requires producers to plant non-resistant corn nearby as a refuge for the pests. The new products will allow for smaller refuge requirements, he said.
Drought-tolerant corn is likely to be available in about two years, Wilson said. Drought tolerance is enhanced by adding a gene that, among other attributes, makes the plant grow a more extensive root system, making it able to extract more water from the surrounding soil. A larger root system also might, in the future, enhance a plant's ability to take up soil nitrogen. The same traits then could be moved to other crops, Wilson said, so, for example, sugarbeets might have both drought tolerance and enhanced ability to scavenge for nitrogen.
Future genetic modifications will give crops better tolerance to cold weather, he said. The future could also mean "smart stack" crops with two, four, six, or eight genes that confer several different actions: insect, herbicide and drought tolerance, Wilson predicted. But he noted that some scientists feel there must be a limit to how many genes can be put into a plant before they have unforeseen consequences.
"They are really designing a plant that is going to meet a lot of the needs of agriculture in the next ten years," Wilson said.
Genetic science also could help develop new crop varieties that can be raised for different markets, Wilson predicted--for example, corn varieties bred for ethanol production, and soybeans high in alpha-linolenic (LNA) acid. Soybeans and other sources of LNA are recommended by the American heart Association. In the body LNA is transformed to omega-3 fatty acids, which benefit the heart.
The University of Nebraska-Lincoln's role in this is to conduct research to provide unbiased information about how effectively the GMO work, Wilson said--"so when growers have questions about how they work, we can provide some answers." Much of the university's role takes place before these products become commercially available, Wilson said.
At the UNL Panhandle Research and Extension Center, research has been conducted on corn with tolerance to 2,4-D and sulfonylurea herbicides.
"It's really an exciting time in agriculture," he said. "Ag industries are looking for new scientists. There's a big demand for students with training in plant breeding, agronomy and bio-chemistry."
For more information about the Panhandle Research and Extension Center visit www.panhandle.unl.edu.