UF/IFAS Gets $4.5M to Continue HLB Fight

Ernie NeffHLB Management

Asian citrus psyllids

Three teams of scientists from the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) recently received nearly $4.5 million in U.S. Department of Agriculture (USDA) funds to study new ways to manage HLB. The funding is part of the $45 million in grants the USDA National Institute of Food and Agriculture’s Emergency Citrus Disease Research and Extension Program recently awarded for 12 HLB research projects.

“These grants build on an existing portfolio of success in finding solutions to combat citrus greening throughout Florida’s citrus groves,” said Michael Rogers, director of the UF/IFAS Citrus Research and Education Center (CREC) and coordinator of the UF/IFAS statewide citrus program. The newly funded studies are summarized below.

Bryony Bonning, eminent scholar and professor in entomology and nematology, leads a team from Gainesville and the CREC in a project that uses a bacteria-derived pesticidal protein combined with gene silencing to manage the Asian citrus psyllid (ACP), which spreads HLB. The long-term goal of the proposed work is to create an environmentally benign approach for citrus growers to control ACP that works within an integrated pest management strategy. The project intends to identify the optimal components for an ACP control product for grower use.

On completion of this project, researchers will be well positioned to produce transgenic citrus and/or trap plants that will suppress ACP populations for use by citrus growers. The results of this research are anticipated to reduce the need for tree removal and replanting as well as reduce insecticide applications and increase yields and fruit quality.

Amit Levy, assistant professor of plant pathology, received a grant to examine how the Candidatus Liberibacter asiaticus (CLas) bacteria interacts with a narrow tissue – known as the phloem – which is buried inside the stem of the citrus tree. There is a significant gap in understanding CLas-phloem interactions in citrus, which has been a major limiting factor for controlling the disease.

Levy and a team of UF/IFAS researchers, the Sainsbury Laboratory and Cornell University scientists plan to address these challenges with a novel seed coat-based system that supports in-depth analyses of phloem dynamics and CLas-phloem interactions in HLB-affected citrus. The project will identify key players required for phloem plugging, host immune response and CLas colonization inside the phloem. These key players can later become novel targets for manipulation with gene editing techniques that can be translated into usable products.

A research team led by microbiology and cell science professor Zhonglin Mou and faculty from the CREC and UF/IFAS Southwest Florida Research and Education Center are working to develop an interim treatment for HLB. The project hopes to turn off the genes that negatively control the citrus immune system and result in disease symptoms in citrus when exposed to disease-causing pathogens. Coupled with other work to target the HLB-causing bacterium itself, the overall goal is to develop new management strategies making citrus varieties highly tolerant to this disease.

The project will use a vector derived from citrus tristeza virus (CTV) to remove negative regulation of the citrus immune system, leading to improved immune response and HLB tolerance. The same CTV vector will also deliver antimicrobial peptides to reduce HLB pathogens.

Source: University of Florida Institute of Food and Agricultural Sciences

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