Florida citrus growers have begun planting trees utilizing gene-editing technology designed to resist citrus greening, a bacterial infection that has affected the state's citrus industry for approximately two decades. The Environmental Protection Agency (EPA) recently approved a gene-edited rootstock, known as CarriCea T1, which is intended to maintain a tree's immune system to combat the bacteria.
Citrus greening, which first appeared in Florida in 2005, is spread by the Asian citrus psyllid, a small winged insect. The infection causes trees to produce bitter, discolored fruit and typically leads to the death of the tree within a few years. Matt Joyner, CEO of Florida Citrus Mutual, stated that statewide production has declined from approximately 300 million boxes of fruit per season in the late 1990s to just over 15 million boxes in the most recent season.
The gene-edited rootstock was developed by the Tampa-based company Soilcea using CRISPR technology. According to Soilcea’s Yianni Lagos, the bacteria often kills half of a tree's root system before physical symptoms appear on the leaves. By focusing on the rootstock, the company aims to enable the trees to fight the infection naturally, potentially reducing the need for chemical insecticides.
While early test plantings show that trees with the gene-edited rootstock appear taller and greener than those without it, the final results remain unconfirmed. Lagos noted that it takes several years for fruit to grow, and researchers must ensure the resulting citrus meets flavor standards. He stated that while current data is positive, the long-term performance of the trees will not be fully known until they reach 10 years of age.
The concrete change for growers currently planting these thousands of trees is a shift from reactive measures, such as protective tents and chemical sprays, to a biological defense built into the tree's DNA. If the technology performs as expected, it could lead to a reduction in insecticide costs and a potential stabilization of fruit supply. However, because citrus trees take years to mature, growers will not know if the fruit is commercially viable or if the trees will survive a full decade until the early 2030s.
The use of CRISPR in this manner sets a precedent for how gene-editing may be used to preserve agricultural sectors facing extinction from incurable diseases. The success or failure of CarriCea T1 will likely influence future EPA approvals for other genetically modified crops. For now, the process remains in a long-term testing phase as growers monitor the growth and flavor profiles of the fruit produced by these newly planted trees.