NYTimes July 20, 1999 Stalked by Deadly Virus, Papaya Lives to Breed Again
By CAROL KAESUK YOON
n the island of Hawaii, on what had been acres of withering, disease-infested plants, farmers this summer are walking among rows of lush green trees, harvesting the world's first crop of genetically engineered papayas.
Steve Ferreira
Healthy genetically altered papaya plants thrived on the right in 1996 as the traditional plants, at left, withered.
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Designed with a gene that allows them to withstand the papaya ringspot virus -- an incurable disease that ruins fruit and can sicken trees to the point of killing them -- these genetically modified plants are already being credited with saving an industry that was on its way out.
In the past seven years as the virus wiped out farm after farm in Hawaii's major papaya growing region, farmers continually sought out new land in what became increasingly futile attempts to escape the spreading disease. Some farmers grew so desperate that they broke into experimental fields and stole genetically engineered papaya seeds before they were approved for use by the Department of Agriculture.
"This industry was dying," said Emerson Llantero, manager of the Papaya Administrative Committee, a research and marketing group supported by papaya farms, most of which are small, family operations of 10 to 20 acres. The new papaya, he said, is a second chance for growers.
In an expanding debate over potential problems with genetically engineered crops, including corn pollen that can kill monarch butterflies and Europe's reluctance to accept genetically engineered foods, some have argued that these novel plants have provided relatively minor tangible benefits.
But farmers like Orlando Manuel, who has abandoned several farms in an effort to escape the virus, would argue otherwise for the new papaya. He said this year that he planted his entire 20 acres in the genetically modified plant known as Rainbow.
"I'd be out of business without it," Mr. Manuel said. "There's nowhere to go. You can run but you cannot hide."
The first of the Rainbow papayas are on sale in grocery stores in Hawaii and on the mainland. Like other genetically modified crops, they have drawn little reaction from the American public. Still, the new papaya is not without controversy or risks.
Organic farmers say they are concerned about ecological risks.
Researchers inserted the disease virus's DNA into the plant's DNA, using a method that had succeeded in protecting other crops, though the exact mechanism of how this works is still being investigated. The risks include the creation of new and more potent viral diseases. Growers also worry that the Rainbow plants may contaminate nearby organic papaya plants by fertilizing them with genetically modified pollen.
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For better or worse, genetic engineering comes to the rescue of Hawaiian farmers.
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"There's been alarm here in the local area," said Roy Smith, president of Hawaii Organic Farmers Association. Mr. Smith said he had been receiving calls from farmers and consumers.
At the same time, the international backlash against genetically modified crops has begun to hit papayas. Dr. Dennis Gonsalves, plant pathologist at Cornell University and one of the creators of the new papaya, said the Mexican Government requested that he destroy experimental fields of genetically modified papaya in Mexico because of growing concerns over possible environmental risks, risks that he says do not exist.
But acknowledging that there could be other risks from genetically modified papaya, Dr. Gonsalves said even these were minimal compared with the benefits.
"People use infinitesimal calculations that this thing might happen and this thing might happen," Dr. Gonsalves said. "If everybody thinks that everything's got to be perfect with genetically engineered stuff, then you can forget about it. We can let the papaya industry die."
Hawaii's farmers have planted about 1,000 acres in Rainbow, one-third of the papaya acreage in the state. Mr. Llantero said farmers were planting the new seeds as fast as they became available.
But despite the risk from the papaya ringspot virus, not everyone is ready to plant Rainbow. Industry watchers say some growers wonder whether there is a sufficient market for genetically modified papayas. Typically 35 percent to 40 percent of the Hawaiian harvest is sold to Japan, where genetically modified papayas have not been approved for sale.
The disease first appeared on the Hawaiian island of Oahu in the 1940's, and slowly spread from farm to farm and island to island. Seven years ago, the virus made its way to the island of Hawaii, where nearly all the state's papayas are grown. Biologists say none of their attempts to cure or prevent the disease -- including traditional plant breeding, removal of diseased trees and a type of plant vaccination -- were effective. (Though called trees, papaya plants are actually extremely large herbs.)
It was Dr. Gonsalves, with colleagues at the University of Hawaii and the Agriculture Department, who began efforts to create a virus-resistant papaya.
Test plots grown in infected areas of Hawaii made clear the genetically modified, or transgenic, plant's ability to resist the virus. Transgenic plants grew healthy and green, side by side with traditional varieties that yellowed, withered and died.
University of Hawaii
The developers of a papaya that is resistant to a deadly virus, from left, are Maureen Fitch, a Hawaii graduate student, Dr. Dennis Gonsalves and Dr. Richard Manshardt.
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But at the same time that Rainbow has solved a problem for some farmers, it may be creating problems for others. Dr. Gonsalves said that organic papaya plants growing near genetically modified papaya could be fertilized by genetically engineered pollen. The fruits produced would then carry seeds with the engineered virus gene. If these seeds are replanted by organic farmers, then they will unknowingly be growing genetically modified fruits, which are by definition, not organic.
"Growers want to know, is there a cost-effective way to make sure that they're not planting genetically modified crops?" Mr. Smith said. "It's difficult to find an affordable path to that kind of integrity." He said Hawaiian farmers produced about $300,000 worth of organic papaya each year, compared with nonorganic papaya, which was worth about $18 million a year to farmers.
In addition, the plant may pose broader ecological risks. Dr. Peter Palukaitis, molecular virologist at the Scottish Crop Research Institute in Dundee, said there were a number of ways in which the new papaya could lead to the creation of new viruses, as is the case whenever a virus gene is inserted into a plant's DNA.
For example, researchers say the genetically engineered virus gene in Rainbow may end up mixing with DNA from other viruses that infect these papaya plants, possibly resulting in the creation of new, potentially more virulent disease-causing viruses. With scientists still working to understand such interactions, it remains unclear how readily new viruses may arise by these means. Other risks include synergy, a situation in which the mere presence of the genetically engineered virus in the plant's DNA makes it sicker than it would be otherwise when infected by another plant virus.
Rainbow does not have wild relatives in Hawaii, so it cannot spread its genetically engineered genes by creating hybrids with native plants.
In addition, Dr. Gonsalves said there appeared to be no risk to humans from eating the protein produced by the virus gene in the papaya. He said people had been eating infected fruits containing the viral protein for years with no ill effect.
Researchers say, despite its apparently iron-clad resistance, Rainbow is unlikely to protect Hawaii's farmers forever. A new virus might make its way to the islands, evolve on the islands, or already exist there in low numbers, and it could overcome the protection now offered by Rainbow.
"We'd all be nuts to say that this is the final solution," said Dr. Richard Manshardt, tropical fruit crops breeder and a creator of Rainbow, at the University of Hawaii. "Biological systems evolve."
Like all Rainbow growers, Mr. Manuel received his genetically modified seeds free from the Papaya Administrative Committee. Unlike nearly every other genetically modified crop that has been approved for commercial use, the new papaya was not produced by profit-motivated seed companies, but by researchers at Cornell University, the University of Hawaii and the Agriculture Department who have allowed growers to use it free of charge.
But Mr. Llantero said the Papaya Administrative Committee was looking into selling the seeds to recoup the costs of seed production, and Dr. Manshardt said the University of Hawaii was also beginning to look into ways of earning money for research from the fruit they helped to create.
Ultimately what will determine the success of the new papayas, which differ somewhat in taste and color from the traditional variety grown in Hawaii, is whether consumers are interested in eating them.
"Food is what you're brought up with,"said Stephanie Whalen, president and director of research at the Hawaii Agriculture Research Center. As for the market that the transgenic papaya can command, she added, "Only time will tell."
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