The Curious Case of the Transgenic Papaya

I’m on Elephant Journal today, doing a Q&A with the scientist behind the Hawaiian transgenic papaya. I’ve excerpted the beginning of the interview (and it’s a bit lengthy, so be forewarned) and hope you’ll read it with an open mind. And please ask questions! I’ll do my best to get answers for you.


Stop by the farmers’ market in Hilo, Hawaii, and you’ll find knobby cherimoyas, avocadoes the size of eggplants, and mounds of papayas, sunset-fleshed and as smooth and sweet as custard.

That wasn’t always the case. Back in the 90s, Hawaiian papaya farmers were faced with devastation from ringspot virus, a plant virus that reduced papaya production by 50% within six years and just kept spreading. Small farmers faced losing their livelihoods when one plant pathologist developed a virus-resistant variety called the Rainbow and distributed the seeds to struggling farmers – for free. Fourteen years later, Hawaii’s small papaya farmers are flourishing.

There’s  a lot to like about this story –the altruism of the researcher, the success of independent local farmers. But there’s one detail that could change everything about how you see it: the Rainbow papaya is genetically modified. A gene from the ringspot virus was inserted into the papaya, where it acts like a built-in vaccine against the virus. In other words, it’s Frankenfood. Or is it?

I say GMO, you think: Monsanto, Big Ag, lobbyists, corporate interests. But none of these played a major role in the GM Rainbow papaya. And for me, that led to an important realization. Genetic engineering technology is not the same thing as Monsanto/ Big Ag policy. It’s a tool. And like all tools, it can be used for good or bad ends.

I’m a skeptic, so I scoured the web for info – agricultural news sites, activist sites, USDA releases, science journals, and blogs. Then I took my questions to the man who developed the Rainbow, Dr. Dennis Gonsalves, retired Professor Emeritus of Plant Pathology at Cornell and now the director of the USDA’s Pacific Basin Agricultural Center. He’s a straight shooter, detailing the successes and challenges of the project with peer reviewed articles and independently verifiable facts. Halfway through our exchange, it hits me: why shouldn’t we always address our science questions to scientists, not lobbyists or activists?

In that spirit, I’ve included his answers to my questions below.

Q: How did you get started with your work on the transgenic papaya?

I was born and raised on a sugar plantation on Hawaii Island but never aspired to be a scientist until I worked as a technician under Dr. Eduardo Trujillo of the University of Hawaii. He let me loose trying to figure out what was causing a disease of papaya and that experience convinced me that I wanted to be a plant pathologist. Dr. Trujillo was a mentor and an inspiration to me as he would periodically to tell me: “Dennis, don’t just be a test tube scientist, but do things to help people.” […] The feeling of joy was incredible when I first inoculated the transgenic papaya in the greenhouse and it showed resistance to PRSV [papaya ringspot virus]. However, that was nice science but how could we translate it to helping people? Naturally, the challenge came when PRSV invaded the Puna district and within a couple of years the Hawaiian papaya industry was in deep trouble. We had a potential solution, had published some nice papers, but did we have the ‘guts’ to try to help the industry survive? We had never attempted to deregulate a transgenic product, as the common thought was that this was the purview of the big companies. But somebody had to do it, and thus we got out of our ‘comfort zone’ in order to help the farmers.

Q: Did you really give out GE (genetically engineered) papaya seeds for free to farmers?

The seeds were initially distributed free to the growers because I believe the industry (Papaya Administrative Committee) got some grant funds from the state to produce the seeds.  Now, the industry produces the seeds and sells them at cost to the growers.

Q: What non-GE methods were used to attempt to combat ringspot virus on Hawai’i?

People have been trying to do classical breeding to get resistance for a long time.  In Carica papaya, there is no resistance.  Some tolerance is found and people have been trying to incorporate these in some lines.  The tolerance is ‘quantitative’ so it can get diluted.  Bottom line, this has not worked for Hawaiian papaya.

Crops rotation, lower densities, etc. have been tried but they do not work because the virus is rapidly transmitted by aphids.  One way that can work economically is to go into virgin areas where it is far from the nearest virus infected papaya, and continually pull out trees as symptoms develop on the new planting. […] Naturally, the more isolated you are the longer for the virus to ‘find’ the papaya field.  One question is:  Environmentally, is it better to clear virgin forest or land to plant papaya than growing virus resistant GE papaya where papaya growing areas already exist?

Keep reading on Elephant Journal…

Photo credit: leahleaf


12 responses to this post.

  1. Thank you Jennifer for such a thorough and thoughtful investigation and report of the issues surrounding transgenic papaya. I hope anyone interested in this topic continues on as I did to Elephant Journal to read your enitre piece which I found to be fascinating. Thank you!


    • Thanks, Donn! I think the issues around genetic engineering are totally fascinating and worth thinking about. The rainbow papaya is considered one of the success stories of genetic engineering — I think I was drawn to it because it wasn’t associated with big corporations or loads of money; it’s a case in which this technology was used to help people. There’s a lot of potential there…we just need to find a way to separate the technology from huge corporate interests that currently dominate it.


  2. Love this! No profit control by industry (forcing farmers to pay exorbitant prices for seeds), which is good. But what I most appreciate about this genetic modification is that there are no losers. These farmers will not be spraying a new chemical working to eliminate a virus that then hurts other species (I guess I could feel bad for the virus?). They just have a stronger crop. Excellent!


  3. This is actually very similiar to Cotton as the year prior to the release of GMO varieties cotto pn farmers in the US lost over 75% of their crop from insect damage that could not be controlled by conventional pesticides.


    • Hi Mike,

      Thanks for sharing that info! I don’t know much about GMO cotton (Bt?). The transgenic papaya story appeals to me because it’s quite distinct from Monsanto and profit, but I think it’s a good thing to be aware of the benefits and costs of GM before coming to any kind of judgment.


      • excellent article on transgenic papaya, I think I will change my mind about all GMO. It sounds some people are doing it to help other people, not like Monsanto, just doing it to screw the farmers and make as much money as they can.

        Jeff Shlosberg


        • Posted by Kitty Ackerman on 08/07/2012 at 19:43

          This is a very rosy picture of genetically modified foods. The down side to this papaya story is that other countries are not so willing to purchase gmo products, including the Hawaiian papaya. We are one of a few countries that have vigorously embraced gmo products. The other problem is this: gmo crops cross-pollinate with other like crops. The contamination of the conventional papaya has been far more widespread than mentioned in this article. Every gmo advocate seems to downplay this very serious problem. What will other papaya growers do when they cannot sell their contaminated crops?


          • Hi Kitty,

            The Rainbow papaya was deregulated (allowed for sale) in Japan earlier this year. Japan has some of the highest standards for allowing GM foods, and Dr. Gonsalves and his team did a number of additional tests for allergenicity and nutrition in order to get the Rainbow deregulated. Japan was a big market for Hawaiian papayas pre-ringspot virus, so the market is recovering now that it allows imports of GM papayas. They are labeled. I have not seen studies on how Japanese consumers are buying these transgenic papayas and would be curious. The last time I spoke to Dr. Gonsalves, he was working on an application to have the Rainbow deregulated in China.

            I’m hearing that you are concerned about cross pollination of GM crops. The papaya is mostly self-pollinating and gene flow studies have shown that there is minimal cross pollination between transgenic and non-transgenic papayas. If you have a source that shows otherwise, I’d be interested in taking a look.

        • Thanks, Jeff! It will be interesting to see if the same technology can make more virus-resistant cassava available for food-insecure developing countries in Africa.


  4. […] mentioned above: It’s Not Easy Being Green ~ The Elephant Journal ~ […]


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