Joseph Cicero, University of ArizonaAs viewed under an electron microscope, a dense biofilm of greening bacteria clings to the gut wall of an infected psyllid.A University of Arizona research group is drilling down to the molecular level to study the citrus greening bacterium, how it enters the insect vector and how it's transmitted into the host citrus plant.
The goal is to find ways to block the transmission process, according to a news release.
Judith Brown, a plant science professor based in Tucson, leads the group.
They are part of a much larger national effort focused on finding solutions to citrus greening, also known as huanglongbing or HLB. It is being funded by a $9 million U.S. Department of Agriculture grant.
Citrus greening is spread by the Asian citrus psyllid, which picks up the greening bacterium as it feeds on infected citrus plants. It then spreads it when it feeds on healthy plants.
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Brown's hope is the group can find a way to disarm the psyllid's ability to transmit the bacterium.
"If we can eliminate its ability to transmit the pathogen, it becomes just a pest, and no longer a carrier of a deadly plant disease," she said in the release.
Brown's group is using the closely related potato psyllid as a model.
They are trying to track how the bacterium moves from the psyllid gut to its mouth parts.
They believe that the bacteria use adhesive proteins that stick to the gut wall.
"We surmise the bacterium break through the gut wall and escape into the blood and that's how they reach the oral region," she said in the release. "But we don't know how that happens. Do they use an enzyme?"
If they could identify the enzyme, they could find a way to prevent it from happening, which would trap the bacteria in the psyllid gut and prevent transmission.