Conversations from the Hall of Fame

Dennis Gonsalves, plant pathologist, interviewed 2007

(Time: ~17:07 minutes)

In ARS I had a little over 5 years of service. The reason for my induction into the Hall of Fame largely had to do with the work I did before I came to ARS. So, I spent 25 years of my career at Cornell University and I retired from Cornell University then went to ARS. 

I am director at USDA Pacific Basin Agricultural Center at Hilo, Hawaii. I actually was born on the island of Hawaii and I grew up on a sugar plantation. I never had any aspirations to be a scientist. I used to work during the summer time in the sugar plantation and I used to use hoeing, hoeing weeds in the sugarcanes and we would spray the weeds with poison to kill the weeds and after doing that a couple of summers I said you know there must be something a little better than that. 

So, I had no aspiration for science but I said I think I better go to college. So, I went to the University of Hawaii and I actually took up agriculture and I wanted to come back to work on the sugar plantation but this time as a supervisor not as a laborer. But midway in my sophomore year the plantations gave up their program so I switched it to horticulture. 

So I got my bachelor's degree and I basically just wanted to find a job. So, this one person's name is Dr. Eduardo Chuheo. He said you know there is a job for a technician on the island of Kauai so we would like you to go there and just be a technician. So I went there and he pointed at this disease of papayas he said "There is a disease of papaya. I don't know what it is but I think it may be a virus." And, here I am with a bachelor's degree, had no inclining of how to do research but he told me "why don't you try to find it out." And, when I started the process of trying to figure out what this was, I knew that this was want I wanted to do. 

So I just had a bachelors' degree, I wanted to an investigator to try to find out how diseases work and how to control them so after working for about ten months I said I did not have enough education. So, I actually asked my supervisor can I go to graduate school? He says "Your grades are kind of low."

But, you know, I thank him because he gave me a chance and they admitted me to the master's program at the University of Hawaii on probation but I was so ready for graduate school and ever since I've had no problem with getting good grades and so forth. So, I would say the challenge to find out what caused this disease of papaya made me want to become a scientist. 

The primary work that led to the Hall of Fame, I believe, is the work that we did with genetically engineered papaya and if you're from Cornell you know that papaya, which is a tropical fruit, does not grow in a very cold climate. So all through my years at Cornell I was doing collaborative work at the University of Hawaii and, me being from Hawaii, it was good to do this collaborative work and basically what we did starting in the 1980s we utilized the new technology of genetic engineering to transfer a small piece of the gene of a virus into the chromosomes of the papaya so transformation and this was a pretty radical hypothesis or approach and basically it was called parasite derived resistance approach and in laymen terms basically it would be called almost like vaccination. 

If you are vaccinated against polio, they basically would inject you with a mild strain of the polio, your body would react to it, produce antibodies then you'd become resistant or immune to the polio infection. So the prevailing idea was that if you put a small piece of the virus into a plant then you would make that plant resistant to that virus. So, the plant we were using was papaya and the virus that we wanted to get the papaya resistant to was papaya ringspot virus. Now why should we use the papaya and papaya ringspot virus? Because the papaya ringspot virus is the most wide spread and important  virus infecting papaya world wide. 

And in Hawaii, back in the 1940s, the virus came into Hawaii destroyed the industry on the island of Oahu so the industry moved to the Big Island and for the next 30-40 years it was fine. The industry was focused on the part of Hawaii were there was no virus. So one day I was in, I went back to the University of Hawaii and the dean of the College of Agriculture asked me "Dennis what would happen if the virus", which was in a town 90 miles away, "got into this region where they are going 95% of Hawaii's papaya?" I said "Oh my gosh you'd get devastated." So I went back to Cornell. I didn't think anything about it. Then two weeks later he calls me up and he said "Dennis I have $5,000. If I give you $5,000 will you start working on trying to develop a control method?" I said "Yes." So this was in 1978.  

So anyway, by the mid 1980s this concept that one could make a plant resistant to a virus by incorporating part of the viral gene into that plant and make it resistant. Well along that time and maybe 10 years before, the technology of incorporating genes into a plant using molecular biology had taken hold so I said "well why don't' we try developing that for the papaya." So myself, I led the team,  which consisted of scientists from University of Hawaii, ARS and I was at Cornell and we had a scientist actually from the Upjohn Company so we started working on this, developing this technology.

So back then PCR was not very common so we had to labor through what we had to do to develop it and we actually utilized a gene gun which was a radical thing they said that if you bombard cells with these DNA on a particle some of that DNA would get incorporated into the chromosome. We were very fortunate that I was at Cornell and the person that had invented this gene gun was right next door so I said 'well let us try to do that'. 

So, we had developed this technique, we developed a number of techniques that we started in earnest to try to insert these genes into the cells of papaya and regenerate into the papayas. So we started that in 1988, 1989. Then lo and behold by1991, we had developed this genetically engineered papaya and it was small stuff that came out of tissue culture and we inoculated that plant with the virus and it was incredible. We inculcated that genetically engineered plant, we inoculated a non-genetically engineered papaya and the non-genetically engineered papaya got sick, stayed stunted because of infection by the virus and the genetically papaya that we had inoculated started to grow just like normal and we said 'oh my gosh our hypothesis worked.' 

So by April 1992 we started a very small field trial with this genetically engineered papaya because we wanted to see how it worked in the field. A month later the long potential invasion of the virus, papaya ringspot virus, into the main papaya growing area of Hawaii is found. 

So then we have the opportunity that we have this genetically engineered papaya that might help control the virus but the virus is moving through and so in May 1992 the virus went into this area where they were growing 95% of Hawaii's papaya.

By October 1994 the virus had spread all through this area and the papaya industry was in danger of being devastated. So we were feverishly working to try to see if what we had developed might work. So we were working very hard. We got the field trial, the initial field trial in 1992, based on that field trial we developed two cultivars of papaya of genetically engineered papaya called 'Sun up' and 'Rainbow'. 

Now because these are genetically engineered crops, they have to be deregulated because genetically engineered crops are regulated by different agencies in the United States. One is the Animal and Plant Health Inspection Service,  APHIS, the other is the Environmental Protection Agency and the other is Food and Drug Administration. We had to get these all approved. So a scientist went through and did all the work and by in May 1998 we had a little celebration in Hawaii and we released commercialized  seeds of this genetically engineered papaya to the industry and that's when the industry started to turn around because before then from 1992 to 1998 the virus was so devastating that the yield of papaya, papaya production in Hawaii decreased by 50%. So we released the genetically engineered papaya in May 1998 and started the recovery of the industry. 

So it was very satisfying work to be able to conceive it from an idea, develop a product, get the product commercialized and then see that thing work in Hawaii and to this day you can go and see people buying these genetically engineered papaya in Hawaii and they sell it in the Mainland US and so it has helped to quote 'save the papaya industry in Hawaii'. 

Advice to Young Scientists 

When I was going for a master's degree, my professor his name was Eduardo Chuheo, he told me 'Dennis don't be just a test tube scientist. Do something to help people'. So that had really stuck with me. I can do the experiments I can do all of this stuff but take it one more step and try to use what you developed to help people and I think the papaya work is a reflection. We developed this thing but we took it the extra step to help the people. 

Then, so, my first words of wisdom is that just don't be a technical test tube scientist in agriculture is more practical thing do something that can help. Then the other thing that I learned going for my PhD at the University of California at Davis, I used to do all of these experiments and work very hard and I gathered this data then I go to my professor and say hey I've got all of this data but the question he would ask me is 'Now Dennis you have all of this data but what have you really accomplished?' Painstakingly he was telling me you know you can have lots of data but have you sifted through the data to see if you have really accomplished something cause there is a huge difference between doing a lot of busy work and sitting back and saying you know what have I really accomplished. 

For young scientists you have to look at that because in the world of science what you accomplish a lot of it is black and white you have to print it and that is measurable so the more you ask yourself what you have really accomplished, that's very important.

And the last thing is and this is a philosophy that I developed myself as I first started my job at the University of Florida way back in 1971. I figured if I'm going to spend so many hours a day working I might as well go for the Big Enchilada. What I mean by that is if you are going to do something you may as well do something important that will have impact. 

So my words of wisdom for the young scientists is that just don't be an academic test tube scientist try to do something good. Develop the skill to be very self-critical to weigh what you are doing and to really see what you really accomplish. Then the other thing is to shoot high to feel that you want to make a great contribution go for the Big Enchilada instead of just being an average old Joe. 

Music and Science 

I like to play music. I play the guitar, I play the ukelele, I play the steel guitar, and my wife and I like to sing and actually in my career I found that music is a good way to break the barrier.

I do a lot of traveling in foreign countries and at first when you go to these countries they look at you coming from the big United States and 'oh my gosh this guy thinks he is too good and so forth' but you know after we have a day in the field, we come back and we start to sing songs and play music and I find that that is when they begin to tell me the inside story of what they are thinking.