by University of Missouri Extension State Beef Genetics Specialist Jared E. Decker, PhD.
Have you ever evaluated a bull, either on paper or visually, and wished you could change one thing about that bull? With new technology, in the coming decades you may have this ability. For simple traits, we have that opportunity now.
With a new set of molecular tools, scientists can now make precise changes to DNA in a process called gene editing. Most consumers are familiar with genetically modified organisms, or GMOs. Gene editing is much more precise than methods previously used in genetic modifications. If the technologies used to create GMOs are sledgehammers, then the technologies used in gene editing are surgical scalpels.
Scott C. Fahrenkrug, founder and chief scientific officer at Recombinetics, has described gene editing this way: Imagine going to the Library of Congress, going to the correct shelf, the correct book, the correct page, the correct paragraph, the correct sentence, and editing a single word. This is the kind of resolution gene editing has. With these methods, we can edit a single base pair out of the 2.7 billion base pairs in cattle DNA, and do so without leaving a trace.
When performing gene editing, scientists can either edit an animal at the embryo stage or can create a clone of a mature animal and edit the clone when it is still an embryo.
One of the traits that has already been edited in cattle is changing the genetic code from horned to polled. Scientists took horned dairy cattle and replaced the DNA sequence that causes horns to grow with the DNA sequence from Angus that stops horn formation. It would take dozens of generations to introduce the Angus DNA variant into Holstein cattle through cross breeding and grading up to high-percentage Holstein ancestry. Rather, scientists were able to accomplish the same task in a single generation.
In other examples from cattle, the DNA variant responsible for double muscling in Belgian Blue cattle was edited in Nelore cattle. This results in considerably heavier muscled Nelore cattle.
In pigs, scientist edited genes enabling complete resistance to diseases such as porcine reproductive and respiratory syndrome. Each year, this disease cost the swine industry billions of dollars.
Genomics research and gene editing often go hand-in-hand. To create an improved animal by gene editing, scientists need to know which DNA sequence (e.g. gene) to edit. There needs to be basic biology research to understand which genes are important in the control or development of that trait. Not always, but often, the basic biology research that occurs is genomic research. This genomic research works to find the DNA variant responsible for differences in the trait. These known DNA variants then can be quickly edited. The larger the genomic-enhanced expected progeny difference data sets become, the more powerful of a resource those become for basic genomics research (see “Agricultural Genomics: Commercial Applications Bring Increased Basic Research Power” in PLOS Genetics, http:// dx.doi.org/10.1371/journal.pgen.1005621).
What remains to be seen is the regulations imposed on these technologies by the Food and Drug Administration (FDA). While the United States Department of Agriculture regulates plant genetic modifications, the FDA controls genetic modifications of livestock. The draft guidance will regard each edited animal as a “drug.” This means each edited animal will have to go through the costly – $1 billion price tag – and time-consuming drug regulatory process. The FDA had an open commenting period on this guidance open until April 19, and many scientists came out against this guidance. Many scientists, such as Alison van Eenennaam, have stated that gene editing is simply precision breeding and should not be regulated any differently.
In addition, in some high-income circles, there may be unfounded concern about the safety of food from gene-edited animals. It is safe to eat a polled Angus animal, so it is also safe to eat a Holstein animal carrying the same DNA variant.
Farmers and ranchers should create opportunities to discuss these issues with politicians and neighbors.
Gene editing opens new doors to increased efficiency and profitability of food production, including growing beef. What trait would you edit in your favorite bull?
For more information on gene editing, see the eBEEF.org fact sheet, titled “What is Gene Editing?,” at http://articles.extension.org/pages/73389/what-is-gene-editing.