Herbicide-Eating Gene May Restore King Cotton's Crown

AUBURN, Ala.— There's a new gene in those cotton jeans, and while it conceivably may help the pocketbook of the person wearing the jeans, it will definitely help the farmer who grows the cotton.

The gene is actually in the cotton plant, which is dubbed "BXN," making it resistant to a particular herbicide. Researchers in AU's Alabama Agricultural Experiment Station have tested BXN cotton for the past three years. Under normal conditions, cotton and most weeds sprayed with the herbicide bromoxynil would die quickly. Weeds around BXN cotton are killed, but because of an extra gene, the cotton is immune to the herbicide.

"BXN looks just like any other cotton--the seed look the same, it grows the same, and visually there is no difference between transgenic (containing an extra gene) and nontransgenic cotton," noted Chet Norris, assistant superintendent of the Tennessee Valley Substation in Belle Mina. BXN cotton was planted at the Substation, which is a research unit of the Main Ag Experiment Station at Auburn, in April. The first crop ever harvested in Alabama under field conditions is ready to be picked at the Substation.

The extra gene in BXN cotton comes from a bacteria that acts much like the video game character in Pac Man, except this bacteria eats bromoxynil. Calgene scientists isolated the gene that allows this bacteria to break down bromoxynil and inserted it into several breeding lines of cotton--one of which is now being tested by AU.

"BXN can be a wonderful tool for cotton farmers, but how well it is accepted will be in large part determined by how well the variety yields and the quality of the cotton it produces," noted Mike Patterson, an AU agronomist who has worked with the transgenic cotton for three years. "The technology is amazing in that we can spray bromoxynil on a row of cotton with the gene and it is unaffected, yet two feet away a row of cotton without the gene is destroyed by the herbicide in a few days," he said.

The big advantage to farmers is that they can wait to see whether weed problems develop, and if so, what type. By using bromoxynil, growers can kill a broad spectrum of weeds with a relatively small amount of herbicide.

Bromoxynil, which is manufactured by Rhone-Poulenc Ag Company, is a contact-killing herbicide that has a short half-life and little soil residual activity. In common terminology that means it is not as much a threat to the environment as other pesticides which are bound to the soil and remain for long periods of time.

Transgenics and biological control methods used in integrated pest management systems are expected to replace about 80 percent of the herbicides used on cotton within the next 20 years. With growers, consumers, and regulatory agencies becoming increasingly critical of potential environmental damage from pesticides, more environmentally tolerant pest management systems are vital to cotton farmers. And, since about 52 percent of the cost of textile operations goes for cotton, environmentally sound production practices could become vital to one of Alabama's top industries.

"We don't expect BXN cotton to be a panacea to save cotton farmers and ultimately the textile industry, but it sure can be a good tool to help insure a stable fiber supply in the future," Patterson concluded.

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Office of Ag Communications & Marketing

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Auburn, AL 36849
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Contact Jamie Creamer, 334-844-2783 or jcreamer@auburn.edu
by Roy Roberson

August 12, 1992