CRISPR-Cas9: the biological Photoshop®
and GMO food regulation loophole
By Tara A. Okuma
Avid Photoshop®
users know how to nip, tuck, add, remove, and edit whatever they desire in photos. Edited and enhanced photos can
be commonly seen throughout fashion magazines, but editing photos doesn’t
change who the person is. Does it? The perceived body may be changed and skin
blemishes may miraculously disappear thanks to Photoshop® but it’s
still the same person in the photo. Photo editing enhances, enriches and
improves photos for advertising and sales. Why not do the same with food—edit,
enhance and improve agricultural crops while decreasing food waste and damage?
Well, food biotechnologists already have! The CRISPR-Cas9 system, a genomic editing tool designed by
biologists, is currently being used for crops and future food. CRISPR (pronounced as “crisper”) stands for Clustered Regularly Interspaced Short Palindromic Repeats and Cas9
is from CRISPR associated protein 9.
This system is composed of two components, a homing device (guide RNA or gRNA)
that locks onto the DNA target of interest like a missile honing in on its
target. The second component is a pair of molecular scissors (Cas9), a guided
enzyme that tags along with gRNA to edit the target DNA and do whatever gRNA tells it to. The CRISPR-Cas genome
editing system is becoming widely popular among food geneticists and is also
being described as a “biological find-and-replace”.
Editing crops
 |
CRISPR-Cas9 is the newest genomic editing
tool that is more precise, accurate, faster and less expensive than older
tools, and genome editing is currently dominating food research and
development. Plant pathologist, Dr. Yinong Yang and his team at Pennsylvania
State University developed an anti-browning white button mushroom (Agaricus
bisporus) using the CRISPR-Cas9 technology. Sliced, bruised and/or damaged
produce such as mushrooms, apples and potatoes undergo browning over time due
to the release of an enzyme called polyphenol oxidase (PPO) from plant cells. Most enzymes
are proteins that catalyze or accelerate biochemical reactions, and since PPO
causes enzymatic browning, Yang and his team removed the gene producing PPO to
prevent the unwanted discoloring. Therefore, mushrooms moving from the farm to
your produce aisle would maintain their creamy off-white color and appearance
of being fresh and undamaged.
DuPont
also announced two types of CRISPR-Cas-edited corn: a drought-tolerant corn that survives drought-stressed
conditions while increasing yield and a waxy corn hybrid that is expected to be available to
farmers within the next five years, pending trials and regulations. The high
amylopectin starch in waxy corn has many food and non-food applications,
including thickening and texture in processed foods and non-food adhesive tapes
and papers. Corn consists of two main starches: amylose and amylopectin. DuPont
turned off the gene producing amylose using the CRISPR-Cas system so that their
waxy corn hybrid mainly produces amylopectin starch, resulting in
cost-effective and increased amylopectin production.
In addition,
Monsanto recently announced their intent to use the CRISPR-Cas system by
entering into a licensing agreement with the Broad
Institute of MIT and
Harvard University. The CRISPR-Cas genome editing system is planned to be used
to help improve global agriculture and will be a great addition to Monsanto’s research
and development team.
Genetic editing vs. GMO
With genetically
modified organisms (GMOs) prominent in the media and the GMO debate still
smoldering, how does genetic editing differ? Genetic modification (GM) involves
inserting foreign DNA segments from one species into the genome of another. For
example, a gene producing pesticide-like protein originally from soil bacteria
was copied and then inserted into the corn genome. Also known as “Bt corn,”
this GM crop produces protein that is lethal to insects and pests that commonly
attack corn crops and causes major crop damage and decay. Whereas genomic editing
techniques consist of altering the native genome, as mentioned with Penn
State’s white button mushroom and DuPont’s waxy corn hybrid. DNA from other
organisms were not inserted into the genome of the mushroom nor the corn,
therefore, both crops are considered genetically edited versus genetically
modified.
Regulation loophole
Since genomic
editing techniques work by editing the existing native genome and does not insert
foreign DNA, the USDA will not regulate genetically edited crops (GEC) if the
edited gene can be attained through conventional breeding (abet very long
periods of time) and foreign DNA segments are not integrated into its genome.
This means that Penn State’s anti-browning white button mushroom and DuPont’s waxy corn hybrid are exempt from USDA regulations,
including the recently approved GMO food labeling bill (S. 764). The U.S. GMO food labeling bill, passed by Congress and
signed into law by President Obama in July of 2016 applies to all commercially
grown GMO crops (corn, soy, canola, and sugar beets) and the foods made from
them. The bill also preempts Vermont’s GMO labeling bill that went into effect
on July 1, 2016, however, will not apply to GECs and the foods made from them.
Similar to what
Photoshop® did for the marketing and advertising industry,
CRISPR-Cas9 is revolutionizing the agricultural industry. Food biotechnologists
and agriculturalists are able to enhance agricultural crops and decrease food
waste, damage, decay, and revenue loss with CRISPR-Cas9 and other genome
editing technologies. GECs will help to improve and create cost-effective food
production for our rapidly changing and growing population. So who’s ready for edited, enhanced and
improved crops to hit the market? I definitely am!