The disease citrus greening was first spotted in 2004. Since then the disease has extended to almost every orange grove in Florida. Such is the extent of the spread that the U.S. Department of Agriculture has implemented a plant quarantine in infected areas in an effort to halt its spread. The infection leads to a yellowing (mottling) of the leaves of the infected plant. This leads to a loss of fruit quality, with the oranges that are borne being unsuitable for sale. Citrus greening is caused by a vector-transmitted bacterium called Candidatus Liberibacter species.
The new treatment has been discovered by University of Florida scientists. Here researchers have identified a small protein from an innocuous bacterium living in Asian citrus psyllids. These are the flying insects that spread the disease from tree-to-tree, as they feed. The bacterium appears able to “cross-talk.” This involves moving to another bacterium within the insects in order to silence so-called “prophage genes” containing viral material in the second – infectious – bacterium. This prevents an insect immune reaction that would likely be detrimental to both bacteria.
Based on this finding the researchers think the protein, isolated from the Wolbachia bacterium, could act as a potential target to develop spray treatments to protect trees against the psyllid insects. In addition such a compound could aid trees in fighting off bacterial invasion. Wolbachia is a natural bacterium present in up to 60 percent of all insect species.
According to lead researcher Dr. Dean W. Gabriel: “”In this case, one bacterium is doing a favor to the whole bacterial community living within the psyllid by shutting down a potential threat to survival of insect host.”
The research has been published in the journal mSphere. The research paper is titled “A Small Wolbachia Protein Directly Represses Phage Lytic Cycle Genes in “Candidatus Liberibacter asiaticus” within Psyllids.”
In related news, University of Florida scientists are also experimenting with lasers in conjunction with antibiotics. Studies have found the combination of a laser and antibiotics to be more effective than simply applying antibiotics.
