loyola90's picture
Can genetic engineering protect plants from disease?

A:Expert Answer

Genetic engineering is already playing a role in protecting plants from disease, and the potential in this area is tremendous. The use of genetic engineering has the potential to help protect plants where other solutions are either impractical or ineffective. Also, the use of insecticides to control insects that are vectors for the transmission of diseases can be dramatically reduced, saving farmers time and money and protecting the environment from chemical sprays.


A few examples:

    • The Rainbow and Sunup papayas from Hawaii were genetically engineered to protect them from the papaya ringspot virus (PRSV) which was devastating the crop. Summer squash were also engineered to protect them from several types of viral diseases. Papayas and squash are on the market now. Squash has been on the market since 1994 and has been of great value to squash growers.
    • The U.S. citrus industry currently faces “citrus greening,” a disease that causes oranges to turn green and fall off the tree. The National Academy of Sciences has warned that citrus greening threatens the very existence of the U.S. citrus industry. Researchers are developing orange trees that incorporate genes from spinach that give them some resistance to the disease. If successful, the trees could save the industry.
    • Plum trees and other stone-fruit trees are threatened by a deadly disease: plum pox virus (PPV). Scientists have developed a GM plum tree that is genetically resistant to the virus. As Cornell University puts it, “The most promising prospect for PPV resistance is genetic engineering.” The virus-resistant trees could protect stone-fruit orchards from incursions of the disease and protect nurseries from harboring the disease.
    • The wine industry is threatened by Pierce's disease, which is caused by a pathogen carried by a sharpshooter insect. Currently, the only control for this disease is aerial spraying of malathion to kill the vector, which is not only undesirable but largely ineffective. The Davis technology, a gene fusion that delivers a one-two punch to the microbe, is a robust, sustainable method that introduces resistance into the vine itself so that it is impervious to the vector and pathogen. This not only saves millions in prevention and control costs but could potentially rescue the industry as a whole.
    • Late potato blight is one of the most devastating plant diseases. It is caused by the oomycete Phytophtera infestans, a pathogen of the potato and, to a lesser degree, the tomato.  It is a $5 billion problem and was responsible for the Irish potato famine.  It requires heavy applications of fungicides to control — no potato has been bred to date that has any measure of resistance to the pathogen. A resistant potato named Fortuna has been developed that contains two genes from a wild-potato relative that confer robust resistance against disease, obviating the need to spray with fungicides.


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rickspalding's picture

There is already evidence of how plants are adapting to the genes. Such as superweeds. These "scientists" will tell you yes, in the same context of BT corn. All they did was add a protein the bugs don't like. So of course they can make plants "disease" resistant. Yet nature will always find a way to defy the odds.

maciak's picture

Hey "ricksdpalding" why all the quotations? Just because a scientifically trianed professional has a different view from you doesn't make them less of a scientist. And what's your beef with disease? Don't you believe plants get sick?

Robert Wager Wager's picture

If people want to see the power of one gene in disease resistance I suggest they read up on the Papaya Ringspot Virus Resistant papayas. By adding one gene from the viral pathogen that destroys papayas the Hawaiian papaya industry was saved. More telling is the countries around the world that grow papayas have active R&D programs to make their own PRSV-papayas.

joanne aubertin's picture

Yes, now they have genetically changed cotton, I believe to actually kill a bug that tries to eat it. Though I may be mistaken on the type of plant. It may have been either corn or soy. One of the three. I wonder what happens to birds if they eat the corn or soy?? Maybe their newborn chicks could be born with 3 heads or die in their shells. Who knows.

WheatLover's picture

While dying in the shell is within the realm of possibility (that was the issue with DT back in the 50s), but a bird being born with 3 heads is a bit of a stretch. It would take an extreme genetic mutation and the ingestion of a single chemical is unlikely to cause that. Though it is interesting to note that similar things have happened naturally before. One of the most famous "Ripley's Believe It or Not" exhibits was a two headed calf, and two headed snakes are occasionally (very rarely) found in nature.

Grace Joubarne's picture

With the explosion of superweeds and superbugs that has been directly linked to the genetic manipulation of plants, it is really impossible to see any benefit of GMOs at all. In fact, Monsanto is now getting permission to use glycophates at 100,000 times the original limits set as 'safe' in an effort to 'burn' off fields overrun by runaway superweeds. We were all eating just fine until GMOs were secretly put into our food system...few were obese, few had disgestive issues and few farmers were enslaved and put into bankruptcy.

Joshua Udall's picture

Rick, just by quoting Jurassic Park doesn't mean its true.

Robert had good point. Here's another example in a way that GMOs are being used to control plant disease (https://www.youtube.com/watch?v=I9scGtf5E3I). While some may be concerned about excessive glyphosate, these innovations have significantly reduced the levels of pesticides. Pesticides are extremely more toxic to humans than glyphosate. For example, Albicarb (http://en.wikipedia.org/wiki/Aldicarb) has been directly linked to 1,000 deaths and is the process of being banned. No such level of toxicity exists for glyphosate, not even close.

corshy1's picture

Kate Plant Pathology Graduate Student's picture

re jusjo:
I think you are refering to GMOs that produce the Bt toxin. Currently Bt cotton, corn and potato have been approved by the EPA and are being produced. Bt is a toxin that only effects specific species of insects, because only a few species have receptors in their guts that the Bt toxin can bind to. Actually the gene for the Bt toxin produced in GMO plants is from the bacteria Bacillus thuringiensis, which is commonly used in organic agriculture and has been used by farmers since the 1920s (altough the first GMO expressing this toxin was released in 1995). If you want to learn more about how Bt toxin works and about GMO plants which express the Bt toxin I recommend taking a look at the University of California at San Diego's website: http://www.bt.ucsd.edu/index.html
It is a good and relatively easy to understand review of the Bt toxin.
Luckily there is no danger of bizarre mutations (like having 3 heads), because this toxin has been researched for almost 100 years and is very well understood. Any birds or mammals that eat the toxin will not be affected because the toxin cannot bind to their guts.

Chris123's picture

For true answers:
Evidence-based examination of the claims made for the safety and efficacy of genetically modified crops: www.gmo-news.com/2013/07/gmo-myths-and-truths/

as pdf download.