Researchers Zero in To Help Make Citrus Canker-Resistant Trees a Reality
September 22, 2022 A team of researchers at the University of Florida have successfully identified a gene (CsDMR6), which impacts a citrus tree’s reaction to the citrus canker pathogen. By editing the CsDMR6 gene in the plant’s DNA to interfere with its normal functioning, the resulting plants develop a strong resistance to citrus canker.
“Gene editing or genome editing is becoming an effective and efficient precision breeding tool for producing new citrus cultivars that can help Florida citrus growers fight against destructive diseases and produce oranges and grapefruits profitably,” says Zhanao Deng, UF/IFAS Professor of environmental horticulture. “One of the factors that limits the application of gene or genome editing is the lack of known genes that can be targeted.”
Deng, fellow UF/IFAS researcher Fred Gmitter, and their team discovered this particular citrus gene, whose editing resulted in strong resistance to citrus canker. The discovery expanded the list of gene targets for editing to improve citrus canker resistance and might broaden the spectrum of resistance to a larger number of citrus canker pathogen isolates.
In a number of other plants, editing the DMR6 gene also led to broad resistance, for example, resistance to several other species of bacterial pathogens. Normal DMR6 gene function inhibits the citrus plant’s ability to defend itself from pathogens that cause citrus canker and possibly Candidatus Liberibacter asiaticus, which causes HLB (aka, citrus greening).
By editing CsDMR6 within the plant’s DNA, scientists have found the resulting plants show resistance to citrus canker. Grapefruit and Carrizo mutants with their DMR6 gene knocked out contain more salicylic acid and express plant defense genes at higher levels.
Next steps include conducting experiments to test these plants’ resistance to HLB.
This research was supported by USDA’s Specialty Crop Research Initiative Emergency Citrus Disease Research and Extension Program.
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