Papaya: A GMO success story

Editor’s note: This is the second story in a four-part series that examines the controversial topic of genetically modified organisms, or GMOs. The series began Sunday and concludes Wednesday.

Editor’s note: This is the second story in a four-part series that examines the controversial topic of genetically modified organisms, or GMOs. The series began Sunday and concludes Wednesday.



Tribune-Herald staff writer

Dennis Gonsalves doesn’t have to travel far to see the fruits of his labor.

The 70-year-old scientist, now retired and living in Hilo, is a short drive from Puna and the papaya farmers he came to know closely more than 20 years ago.

Growing up in Kohala during the plantation days, Gonsalves went to the University of Hawaii at Hilo, hoping to return with an education and a job as a boss for one of the sugar companies.

Life took him in another direction. Finding a passion in scientific research, he ended up as a plant pathologist at Cornell University, where he helped make genetic history through the creation of the virus-resistant Rainbow papaya, credited with bringing the industry back from the brink.

“If you drove here in the 1990s, you would see nothing but dead (papaya) trees,” he said recently as he drove his pick-up truck toward the farm of Alberto Belmes in Keaau.

Tucked away behind Highway 130, the farm stretches over 100 acres with a seemingly endless forest of the tall but slender papaya trees planted in neat rows and topped with their green oblong-shaped fruit. Some of the fruits are displaying a yellow tinge as they ripen, and are being harvested by workers using long pickers needed to reach the top of trees that are as tall as 15 feet.

Each tree is transgenic and can trace their origins back to Gonsalves’ lab.

For Belmes, a Filipino immigrant who said his farm was “wiped out” by the ringspot virus, genetically-modified papaya has been nothing short of a life-saver.

“I still would be out of business,” said Belmes, his friendly eyes now matching the earnest tone in his voice.

“It’s hard to get a job in Hawaii.”

As protests against genetically modified food grow, the Rainbow papaya is frequently cited by scientists as a transgenic success story.

Belmes’ farm was one of the first to adopt the Rainbow papaya, which carries a protein coat gene from the virus, allowing it to reject the pathogen.

It didn’t take long to realize its benefits.

“When we started … everyone was jealous,” Belmes said.

“I’m so happy we are all Rainbow. Not me and myself, for everyone that has a job to go to work.”

Rainbow papaya makes up about 77 percent of the crop now, with some farmers still growing the non-transgenic Kapoho Solo to export to markets, like Japan, that are slow to embrace modified food.

But overall, papaya production remains a fraction of its peak.

In 2010, the most recent data available, there were 30.1 million pounds of papaya harvested in the state, almost all of it on the Big Island, according to the state Department of Agriculture.

Hawaii’s largest yield was 80.5 million pounds in 1984. In 1992, the virus hit Puna, which was growing 53 million pounds of papaya annually.

By the time transgenic papaya was commercialized in 1998, production had been cut in half and most trees were infected, Gonsalves said.

While production remains significantly below pre-virus levels, Gonsalves and other scientists believe there wouldn’t be much left without it.

“There’s no papaya industry. Simple as that,” he said.

Before being located almost entirely in Puna, papaya had been mostly grown on Oahu. Those crops were hit by the virus, carried by aphids, in the 1950s, causing the re-location to the Big Isle. It was first detected on the island in the 1970s in Hilo before spreading to Puna.

A hindrance to the growth papaya industry is the acceptance of transgenic crops abroad.

Japan, which has historically been a major consumer of Hawaii papaya, didn’t accept the Rainbow variety until December 2011, and it still makes up a tiny fraction of exports to the country.

The Pacific neighbor has also required non-transgenic papaya to be tested to ensure its genetic purity, Gonsalves said.

Japan imported $1.3 million worth of papaya in 2012, about 16 percent of all of Hawaii’s papaya exports.

Gonsalves expects that to continue to grow over time as consumers elsewhere begin to accept the Rainbow papaya as safe, but at the same time, hints that lingering concerns over the safety of modified food may slow that down.

The transgenic papaya had been thoroughly tested, Gonsavles said, for impacts on nutrition and allergens. The transgenic and non-transgenic fruit were found to be “substantially equivalent” in terms of nutritional value, meaning there are no significant variations, according to a 2011 study by the Pacific Basin Agricultural Research Center in Hilo and the University of Hawaii.

There are also no increased risks for allergens, said Gonsalves, who directed PBARC until his retirement in December, and he believes health concerns are unwarranted.

“Some people say, ‘I never eat transgenic papaya.’ Great. But don’t tell me it’s not safe,” he said.

For some organic farmers who seek to grow non-modified crops, Rainbow papaya is not a welcomed neighbor.

Geoff Rauch, a Pahoa farmer, said the transgenic fruit makes it harder to ensure that his produce isn’t modified.

Genetic purity requires vigilance, and presents an additional challenge for organic farmers, he said.

“Every year, I get it sampled so I can tell (customers) I am growing non-transgenic papaya,” Rauch said.

Loren Mochida, director of agriculture operations for W.H. Shipman, said he believes transgenic and non-transgenic papaya growers can co-exist, noting that some commercial growers still have both varieties on their farms.

“Actually it (Rainbow papaya) helps the organic guys,” he said. “… It keeps the virus pressure down on the surrounding areas.”

Another study PBARC published in 2011 showed low levels of pollen drift between Rainbow and non-transgenic papaya as long as the plants were hermaphrodites.

The study found that between 0.8 percent and 1.3 percent of tested Kapoho Solo hermaphrodite trees grown adjacent to Rainbow papaya produced transgenic genes. Nearly all of commercial plants are hermaphrodites, which self pollinate.

The transfer rate was much higher for female plants at 67.4 percent.

Gonsalves notes that only the seeds carry the new genes, not the fruit itself.

“If there is cross-contamination, that crop can still be sold as an organic crop,” he said.

The story of transgenic papaya doesn’t end with the Rainbow variety or the ringspot virus.

David Christopher, chair of molecular biosciences and bioengineering at the University of Hawaii at Manoa, said he is working to develop papaya that is resistant to a fungus that also frustrates growers.

The pathogen is related to the bacteria that caused Ireland’s potato famine, he said, and he believes he can eliminate it by adding a grape gene to the DNA of papaya.

“If we can (get) consistent results, farmers in humid wet regions will not have to spray their papayas with chemical fungicides, leading to a cleaner and safer farming conditions,” he said in an email.

So far, full resistance hasn’t been reached, but the research is promising, with field trials possibly a few years away, Christopher said in a phone interview.

Belmes, who has a few trees killed by the fungus, said he would be happy to try it.

“Chemicals for spraying is so expensive,” he said.

Gonsalves said farmers also have to let fields go fallow for three years to combat the fungus.

The fungus is particularly problematic during times of extended rain, said papaya grower Ross Sibucao.

“In wet weather, at least 20 percent or 30 percent” of trees are impacted, he said.

“It can get pretty bad.”

The non-transgenic Kapoho Solo is slightly more tolerant of the fungus than Rainbow, said Gonsalves, though both are hit hard.

Without a resistant variety, traditional cross-breeding becomes an unlikely solution, Christopher said.

Scientists came across the same problem with tyring to defeat the virus.

Few plants are related to papaya, making it difficult to cross-breed resistance.

“Papaya is a problem because it doesn’t have any wild relatives,” Christopher said.

“It’s really genetically uniform.”

Recently, a researcher in Australia had some success crossing papaya with a ringspot-resistant plant from South America known as calasacha or vasconcellea quercifolia.

But there were problems.

The resistance failed to transfer passed the first generation and the hybridized plant didn’t produce fruit that was commercially viable, said Richard Manshardt, a horticulturist with UH-Manoa.

Manshardt said UH scientists also picked up on the research, but it doesn’t look promising and funding is expected to run out.

“At this point, it doesn’t look like we got anything useful from that experiment,” he said.

Despite continued controversy over genetically modified food, Gonsalves believes he and other scientists made the right decision with papaya.

In presentations, he said he always shows a picture of a woman in Thailand planting one of his immunized papaya trees. Those trees were protected from the ringspot virus but couldn’t pass on resistance to the next generation, preventing them from being a solution to Hawaii’s problem.

Still, it highlights the point he tries to pass to his audience.

“That to me, it brings us back to why we’re doing something,” Gonsalves said.

“In the end, we did it to help people.”

Still, he doesn’t see all uses of genetic engineering as being equally altruistic. He believes its uses need to be looked at case by case.

“This is a powerful tool …,” Gonsalves said.

“The big question is, ‘Is it causing harm to the environment, causing harm to human safety?’

“To my estimation, the answer is we have acted good.”

Email Tom Callis at



Record harvest:

80.5 million pounds, 1984

2010 harvest: 30.1 million pounds


1970s: Ringspot virus found in Hilo

1991: Scientists successfully develop transgenic papaya that is virus resistant.

1992: Virus hits Puna. Production at 53 million pounds.

1998: Rainbow papaya approved by regulatory agencies for commercialization. Production in Puna at 26 million pounds.

2012 EXPORTS in value

Total: $8,637,162

Canada: $5,132,901

Japan: $1,376,097

Hong Kong: $264,592

China: $943,543

Germany: $110,973

What is Rainbow papaya?


Scientists added a gene from the ringpsot virus into a Sunset papaya.

Called SunUp, this variety was then crossed with Kapoho Solo papaya, which is preferred for export, to create Rainbow. Rainbow papaya now accounts for 77 percent of the state’s crop.

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