James and the Giant Corn Genetics: Studying the Source Code of Nature

Photo Reeding, Flickr (Click for photo stream)

Scientific Name: Carica papaya

Genetically Engineered Trait: Resistance to the papaya ringspot virus

Details of Genetic Engineering:

In the 1990s papaya ringspot virus was in the process of wiping out the Hawaiian papaya industry, then the second largest fruit industry in Hawaii. Conventional approaches such as selective breeding for resistant papayas or attempting to grow trees in isolation had failed. The virus is transmitted by small sap-sucking insects such as aphids. Infected papaya trees can be recognized by the discolored rings on their fruit (that the virus gets its name from) yellow leaves, and most importantly from a papaya farmer’s perpsective a 60-100%* loss of fruit production.

Resistant papayas were created by a collaboration between the USDA and the University of Hawaii (with help from Cornell University where the early versions of ballistic transformation** were being developed at the time) by giving papayas a gene from the papaya ringspot virus itself. It worked. Resistant papayas are so successful that they’re used to protect organic papayas from the virus. (second half of the article)

Another point to keep in mind in this case is since the transgene introduced into GE papayas to protect them from viral infection came from the papaya ringspot virus and many organic papayas are still infected with the virus, the average organic Hawaiian papaya has HIGHER concentrations of the papaya ringspot virus protein than the unnatural genetically engineered ones***

Papaya Tree Picture mattkoltermann, flickr (click for photostream)

About Papayas:

The papaya was originally domesticated in central America, and is now grow around the world. Papaya’s actually have a high concentrations of an enzyme that breaks down proteins called papain. A sufficiently concentrated extract might be able to dissolve flesh (though I don’t know that anyone has tried it) and that ability is showcased in the use of unripe papaya juice to tenderize meat.

Special Bonus Section:

While transgenic papayas have been a huge hit in Hawaii, their adoption in the rest of the world has been quite slow. Because the papayas are the product of non-profit and government agencies, there’s no one with a profit motive in their adoption, and leaving local agricultural advocates and researchers outnumbered and outspent by anti-GMO NGOs that draw most of their financial support from Europe. A great case study of the problems they face was presented a year and a half ago in Plant Physiology: “Forbidden Fruit: Transgenic Papaya in Thailand” It’s well worth a read as both a fascinating story in it’s own right, and an example of the tactics that can be used against genetic engineering when scientists aren’t engaged enough to act as a check on misinformation. To close my profile on papaya, let me quote the conclusion of that article:

It is time to meet the press. Although scientists are not generally trained in media communication, who is better qualified to discuss the risks and benefits of GE crops? If scientists do not undertake this task, where will the public get its information?

If the next generation of biotechnology crops is to make an impact on those who arguably have the most to gain and have yet to reap the benefits of the first generation—those of the developing world—then it is time for plant biotechnologists to move beyond the bench, kick around in some barren soils, man a water buffalo for a day, meet the people whose lives will be impacted, and display the same amount of passion for having their technology used in the field as they have for developing it in the laboratory. It is time to get organized, get political, get heard, and get out of the lab. Otherwise, the fruits of this fascinating research may remain forbidden.

*Losses of production per country or per region are often much greater. If papayas are less productive, fewer people will choose to grow them, so increasing yield per plant actually has a multiplicative effect as more people get back into the growing papayas.

**The original gene gun was basically a modified .22 caliber rifle. The principle of a gene gun is basically if you throw DNA hard enough at a layer of cells some of it will end up in the nucleus and get incorporated into chromosomes by natural repair mechanisms. And the crazy thing is that it actually works!

***This is an old statistic, that I believe dates from before genetically engineered papayas were incorporated as a layer of protection around organic papaya production. (The idea is aphids traveling towards the organic papayas will first reach the virus resistant papayas, bite them where the virus is ineffective.)