U.S. Department of Agriculture Agricultural Research Service (USDA ARS) scientists have discovered a way to augment a citrus tree’s natural resistance to pathogens, including HLB. The scientists are in the Crop Improvement and Genetics Research (CIGR) unit in Albany, California.
According to James Thomson, a geneticist at CIGR, by incorporating receptors that can recognize pathogens, scientists are able to activate a plant’s own innate immune responses. The challenges in developing this approach were to identify the appropriate HLB-recognition genes, incorporate enough of them to be effective, and design a pathway to introduce them into trees. One way to deliver the genes is to use agrobacteria.
“Agrobacteria is a microbe that originated in soil, but has been turned into a plant engineering tool,” Thomson explained. “Essentially, you clone the DNA of interest — in this case, from plants that have a natural resistance to the pathogen of concern — and add it to the agrobacteria. Then the agrobacteria adds that specific bit of DNA to the genome.”
Getting the “loaded” DNA into targeted trees is the next step. “This is all done in the lab through tissue culture,” Thomson said. “A bit of the original plant is cut into little pieces and mixed, temporarily, with the agrobacteria. The plant pieces are then cleaned of agrobacteria and encouraged to regrow into a whole plant.”
The researchers’ plan is to transfer their knowledge and technology to citrus tree nurseries. Growers will be able to purchase the trees they need, when they need them, Thomson said.
“I see (this) HLB-fighting technology being deployed in the next several years,” Thomson said. “There are already a series of genes that can detect and fight HLB; the biggest problem is how to distribute the solution. This project has made strides in identifying genes from other plants that activate defense responses in the presence of HLB.”
Source: USDA ARS
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