NC State Extension

What Crops Have a GMO Trait? What Do the Traits Do and What Is the Benefit of These Traits?

There are 8 commercially available genetically engineered (GE) crops in the US. They are alfalfa, canola, corn, cotton, papaya, soy, squash, and sugar beets. A potato and apple have been approved but are not commercially available at this point. Genetically engineered insect resistant brinjal is currently approved and grown in Pakistan. Brinjal is what we call eggplant in the US.

The traits that are currently available include herbicide tolerance, insect tolerance and disease tolerance. There are also crops that have been developed that improve nutritive value of foods, some of which are close to being commercialized. Who benefits is mostly related to the trait rather than the crop so I will discuss the benefits and who benefits based on the traits.You could break down who benefits into benefits for the consumer, environment, farmer, and the needy. Technologies that benefit the environment would be thought to beneficial to the general public as well.

Herbicide tolerance is often seen as only beneficial to the farmer. However, herbicide tolerance, in particular Roundup (glyphosate) tolerance, has led to an increase in reduced tillage. Reduced erosion is a benefit to the environment and to the public. Reduced tillage systems with herbicide tolerant crops also lead to reduced fuel use on farms. This is definitely a benefit to the environment.

Herbicide tolerance is often said to have increased herbicide use due to herbicide resistance. Herbicide resistant weeds are often referred to as “superweeds”. Weed resistance is not unique to farming genetic engineered (GE) crops. Farmers have had problems with weed resistance to herbicides before genetically engineered crops were available. In fact, the number of newly identified herbicide resistant weeds per year has slowed down since the adoption of GE herbicide tolerant crops.

The often reported increase in herbicide use due to GE crops is not as simple as it might appear. The total amounts of herbicides decreased during the first years of GE crop production and then has increased almost to levels prior to GE cropping due where herbicide resistant weeds have appeared. What has changed is the environmental impact. Cornell developed an environmental impact quotient that includes dermal toxicity, chronic toxicity, systemicity, fish toxicity, leaching potential, surface loss potential, bird toxicity, soil half-life, bee toxicity, beneficial arthropod toxicity, plant surface half-life. GE crop herbicides systems have a lower impact on the environment based on these calculations.

Genetic engineering is not the only way that herbicide tolerant crops have been produced. Mutation breeding has been used to create commercially available herbicide tolerant crops that are not subject to the regulations and testing that are required for GE herbicide tolerant crops.

Insect tolerant GE crops have led to reduced insecticide use. Corn and cotton are crops that have been genetically engineered for insect tolerance in the US. This technology is certainly a benefit for the farmer due to reduced insecticide applications. Reduced insecticide use benefits the environment because of lower impacts of farming on non-target species such as bees, beneficial insects and fish. Insect tolerant crops are also especially beneficial to farmers in developing countries who have less access to insecticides and often the only insecticides they have access to are more toxic older insecticides. These farmers often spray by hand and do not have proper safety equipment to handle or apply pesticides safely.

Papaya is the only commercially available GE crop that has been engineered for virus resistance. This technology saved the papaya industry in Hawaii. This technology benefits the environment as insecticide sprays are not need to control insects that vector the virus. The availability of papaya is a benefit to the consumer. Virus resistance has already been engineered for plums and is ready if plum pox virus becomes more serious. Scientist are working on engineering resistance to diseases in other crops like bananas, grapes and citrus. Citrus greening is a virus that is a serious threat to the citrus industry in Florida and in other parts of the world. Like with papaya, the use of genetic engineering could help save the industry. Currently the only methods of control are removing diseased trees and spraying insecticides in an attempt to limit the spread of the disease. These efforts have not been very successful. GE citrus crops may benefit the consumer by keeping citrus available in markets and benefit the environment by reducing insecticide applications.

A GE blight resistant potato (Fortuna) has been developed but has not been commercialized due to fears about consumer acceptance. Blight is what caused the Irish potato famine. Blight still is a major pest in potatoes. A blight resistant potato would benefit the environment by reducing fungicide applications.

Bananas are under threat from several diseases and there is current research developing GE disease resistant bananas. Bananas make up a large portion of the diet of some African countries. Conventional breeding for disease resistance in asexually propagated crops like bananas is difficult.

Both apples (Arctic apples) and potatoes (Innate potatoes) have been genetically engineered so that they do not brown when cut open. The potato also reduces acrylamide in potatoes. Acrylamide has been linked to some cancers. Both products could benefit consumers by reducing food waste. The small company that produced Arctic apples hopes the ability to serve sliced apples that do not brown will increase apple comsumption by children.

Another category of GE crop traits is improved nutritional content or health benefits. Examples are purple tomatoes and pink grapefruit with increased levels of antioxidants and golden rice which is engineered to reduce vitamin A deficiency. These crops are not available at this time but could be available in the near future. Golden rice would be beneficial to the needy in developing countries. About 500,000 people go blind every year due to vitamin A deficiency. About half of those die within a year due to other complications related to vitamin A deficiency. There is also active research utilizing genetic engineering to reduce allergens in such foods and peanuts and rice.

The final category is traits for industrial processes. Two examples would be Amflora potato and Enogen corn. Amflora potato was engineered to have reduced levels of amylose to make it more conducive to some industrial applications like paper making. Enogen corn contains a transgene from a bacteria that produces alpha amylase, an enzyme that breaks down corn starch into sugar. Enogen corn can be used to make ethanol with less energy and water than conventional corn. That would be an environmental benefit.

One GE food product that is rarely mentioned is cheese. Over 90% of the cheese is made using genetically engineered microbes rather than calf stomachs (rennet).

One can see that each trait is different and that each trait may benefit different different parts of society, and in many cases a trait has more than one beneficial attribute.

Keith Edmisten, Professor of Crop Science

Written By

Photo of Dr. Keith EdmistenDr. Keith EdmistenProfessor of Crop Science & Extension Cotton Specialist (919) 515-4069 keith_edmisten@ncsu.eduCrop and Soil Sciences - NC State University
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