Opinion: Using GE to tackle papaya virus has lessons for wheat rust

Editor’s note: this post was contributed by Pamela Ronald, professor of plant pathology.

In a recent op-ed piece in the New York Times, (“Stem Rust Never Sleeps,” April 26, 2008) Nobel Peace Prize winner Norman Borlaug describes a new strain of stem rust fungus that could reduce world wheat production by 60 million tons, or 10 percent of the world wheat harvest.

“If millions of small-scale farmers see their wheat crops wiped out for want of new disease-resistant varieties, the problem will not be confined to any one country. Widespread failures in global wheat production will push the prices of all foods higher, causing new misery for the world’s poor.”

Is there anything we can do to avoid a global crop failure of this magnitude? Yes. Borlaug argues that it is critical to continue American support for the international agricultural research centers (the State Department is recommending ending this support as well as support for important research centers, including the U.S. Department of Agriculture’s essential rust research laboratory). If publicly financed international researchers move together aggressively and systematically, high-yielding replacement wheat varieties can be developed and made available to farmers before stem rust disease becomes a global epidemic, Borlaug says.

The story of papaya provides an excellent example of how plant biologists can thwart such a disease.

In the 1950s, the entire papaya production on the island of Oahu, Hawaii was decimated by papaya ringspot virus.

Because there was no way to control the disease, the papaya farms moved to the Big Island of Hawaii where the virus was not yet present. At the same time, Dennis Gonsalves at Cornell University and coworkers initiated research to develop strategies to control the disease. (Gonsalves earned his doctorate in plant pathology from UC Davis.)

In 1992, the virus was discovered in the papaya orchards on Hawaii and by 1995 the disease was widespread, creating a crisis for Hawaiian papaya farmers. By 1998 papaya production had dropped to 26 million pounds.

Fortunately, Gonsalves’ group was able to develop papayas resistant to the virus by using genetic engineering. They spliced a small snippet of DNA from a mild strain of the virus into the papaya genome. Similar to human vaccinations against polio or smallpox, this treatment immunized the papaya plant against further infection. The genetically engineered papaya were highly resistant to the viral strain.

After release of the new papaya seeds to farmers in May 1998, production rapidly increased with a peak of 40 million pounds in 2001.

The story of the Hawaiian papaya is an example where genetic engineering was the most appropriate technology to address a specific agricultural problem. There was, and is, no other technology available to protect the papaya from this devastating disease.

This brings us to the question, what if genetic engineering, the most promising method for controlling stem rust, is used to develop new high-yielding resistant wheat varieties? Will the public’s anxiety about the process of genetic engineering, a technology that has been used in agriculture for 15 years (and in medicine even longer) without a single negative environmental or human health effect, paralyze us and prevent release of life-saving wheat varieties?

Just as the public’s embrace of the political strategy of “manufactured uncertainty” about global warming has delayed much needed action, so can whispers of uncertainty about GE delay our focus on helping feed the poor and malnourished.

Pamela Ronald is a professor of plant pathology at UC Davis and co-author of a new book, “Tomorrow’s Table,” about the potential for partnering genetically engineered crops with organic farming to achieve sustainable food production. She writes about these and related issues on her blog, Tomorrow’s Table.

Footnote: The genome of the domestic papaya was recently published in the journal Nature. Among the authors are Gonsalves, currently at the USDA’s Pacific Basin Agricultural Research Center in Hilo, Hawaii and Ming-Cheng Luo, associate research geneticist at the Department of Plant Sciences at UC Davis. Reuters story on the papaya genome here.

One response to “Opinion: Using GE to tackle papaya virus has lessons for wheat rust

  1. I am always arguing that there’s a good reason genetic modification should be used to ameliorate food shortage in the world. Making corporations like Monsanto look bad is not the best thing to do. The world should look beyond corporations. Actually criticism against genetically modified foods should be directed at scientists and not companies that employ them. Pamela makes a very good point about using genetic engineering to tackle wheat rust. By the way, blogger James has written about Pamela (http://www.gmoafrica.org/2008/04/uc-davis-researcher-blogs-on-genetic-engineering.html) and how she is promoting awareness about genetic engineering, a topic that is poorly understood by the public. Other scientists must also come on board and help the public understand this topic.

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