Gene Editing Brings Hope to Florida Citrus Growers Battling Greening Disease

Florida’s citrus industry faces a tough battle against the disease known as citrus greening. The disease, spread by the Asian citrus psyllid insect, disrupts trees’ immune systems, leading to bitter and discolored fruit before the trees ultimately die. Since its arrival in Florida in 2005, citrus greening has drastically reduced the state’s citrus output, dropping from around 300 million boxes of fruit each season in the late 1990s to just over 15 million boxes this past year.

Attempts to combat the disease have ranged from using tents and sprays to employing genetic modifications. In a promising development, citrus growers have started planting genetically modified trees designed to resist the disease. This advancement follows the Environmental Protection Agency’s recent approval of gene-editing techniques.

Soilcea, a company based in Tampa, has developed a rootstock called CarriCea T1 using CRISPR gene-editing technology. This modified rootstock enables trees to maintain their immune systems, reducing reliance on insecticides. According to Soilcea CEO Yianni Lagos, addressing the rootstock is crucial. By the time symptoms like yellowing leaves appear, half of the tree’s root system has already perished.

The test field in Thonotosassa, Florida, shows promise. Here, trees with the CarriCea T1 rootstock appear taller and greener compared to those without the modification, which exhibit signs of disease. Ron English, who manages the test field, notes the significant difference in leaf size and health between modified and non-modified trees.

The ultimate proof of success for the modified trees will come with the fruit, which takes years to mature. Evaluating both growth and taste of the fruit will indicate if the genetic modifications truly work in the long term. As Lagos states, the data looks promising but observing a tree after 10 years will provide definitive answers on its performance.