Saving Citrus: Using genetics to boost resistance to citrus greening

PROBLEM

• Citrus greening is spreading rapidly in the U.S. and threatens to destroy our nation’s citrus industry.

SOLUTION

• By identifying the critical genetic factors that lead to resistance to citrus greening, scientists can breed new citrus varieties that will limit the disease’s impact. 

Drive through any orange grove in Florida and you are likely to see the blotched yellow stain of disease attacking the very heart of the Sunshine State. Huanglongbing (known as “HLB” or “citrus greening”) has infected citrus farms in every Florida county and caused billions of dollars in damage to one of the state’s primary crops.

Citrus greening is caused by a bacteria that hitches a ride in a tiny insect, the Asian citrus psyllid. Once infested, trees produce undesirable fruit and slowly decline from a combination of deteriorating roots and tree canopy dieback. There is no known cure for citrus greening.

At University of Florida’s Institute of Food and Agricultural Sciences, researchers are working to save Florida’s citrus industry by applying a new gene-editing technique. Known as CRISPR, it allows scientists to speed up the changes that might naturally occur in organisms by editing segments of DNA to achieve a desired outcome, such as improved disease immunity.

When a tree is exposed to the bacteria that causes the disease, it doesn’t recognize the threat and instead welcomes the bacteria into its cells. Scientists are seeking an “off switch” in the genome of orange trees that will close its doors to the spread of citrus greening. “Our approach to protect citrus trees against HLB is to increase the potential of citrus’ own immunity,” said Dr. Wang. With the latest advances in gene editing, the team is helping the orange trees protect themselves to ensure that Florida’s citrus industry survives and thrives once again.

“It has been a joy to witness the explosion in genetic and genomic technology, which has allowed us to achieve accomplishments in my lifetime that we could only dream of at the beginning of my career.”
– Fred Gmitter 

RESEARCHERS

• Fred Gmitter, PhD, University of Florida
• Nian Wang, PhD, University of Florida

FUNDING

• USDA NIFA AFRI