Selective Breeding Gets Modern — in order to sidestep fears of genetically modified foods:
Some of the largest agricultural biotech companies in the world, including Monsanto and DuPont, are turning to marker-assisted selection, or MAS, as a way to circumvent the controversy surrounding genetically modified foods.Scientists say it’s an efficient and relatively noncontroversial way to create designer fruit and vegetable crops with superior disease and pest resistance, as well as enhanced flavor, texture, skin color or shelf life.
MAS involves analyzing plants for genetic markers associated with desirable traits, then using conventional breeding methods to introduce the genes into a host. The markers are used to quickly identify which seedlings are the superior progeny.
For example, a wild apple variety might have a brilliant red skin. In order to bring that trait to a domesticated apple, researchers first scan the apple’s genome for the gene that determines skin color. Then, looking at the wild apple, they search the chromosome containing the skin color gene for a unique and easy-to-identify segment, which becomes the marker. After crossbreeding the two apple trees, scientists look for the genetic marker rather than waiting a few years to see which of the seedlings picked up the red skin trait.
The technique allows researchers to sort new hybrids in the lab long before any fruit is grown. This involves taking a DNA sample from each sapling and using methods such as gel electrophoresis to look for the red skin marker in the genetic code. Companies are compiling databases of MAS genetic markers, and while some are making the data freely available, others are treating marker information as a trade secret.
Most fruit and vegetable species have far more wild varieties than we see in the grocery store, and many contain valuable traits, such as pest resistance or luscious fruit, that could be bred into common varieties.
Scientists at Seminis, a seed company acquired by Monsanto in 2005, found that a wild tomato variety had a natural resistance to tomato yellow leaf curl virus, which causes a disease that can devastate domesticated tomatoes. They identified the gene responsible for the resistance and bred it into a domestic variety.