The U.S. Department of Agriculture (USDA) is examining different ways to deliver therapeutics to citrus trees for management of citrus greening disease, also know an huanglongbing (HLB).
The hope of the USDA initiative is to establish an HLB-therapeutic molecule and identify the most cost-effective strategy to deliver these molecules to growers. The project is in collaboration with the University of Florida Institute of Food and Agricultural Sciences.
Robert Shatters, USDA research molecular biologist, is the lead on this project. He gave an update on the research efforts during the 2021 Florida Citrus Show.
According to Shatters, the importance of this work and the discovery of novel therapeutics is to ensure the solutions to citrus greening are based on multiple control points, avoiding resistance to any one approach. The goal is to also improve the economics of delivery since some of the most promising strategies are still too expensive to roll out on a large scale.
A major focus of the research is delivery strategies. Field trials using three separate delivery methods are being conducted, including using two novel delivery methods invented and patented by the USDA team. Shatters says growers need multiple delivery options to maximize their ability to manage the disease in the field. Plus, some delivery methods may be better suited to certain strategies.
One of the novel delivery methods Shatters discussed during his presentation involved using a plant-host activated-cell transplantation for pest and pathogen immunity. A key objective is to deliver genetic engineering solutions to pest and pathogen issues without producing a genetically modified crop. According to Shatters, this strategy can be used to treat existing, HLB-infected trees in the field and reduces exposure of the treatment to non-target organisms in the environment. This strategy is currently showing promise in greenhouse delivery to potted plants.
Direct infusion and transgenic delivery are also being evaluated. As research continues, commercial potential for these therapeutics will also be evaluated.