Genome Editing of Citrus Susceptibility Gene CsLOB1 Confers Resistance to Citrus Canker

Citrus production has many biotic challenges, such as bacterial canker and Huanglongbing (HLB), and using resistant varieties is the most effective way of controlling these diseases. However, traditional breeding of citrus is challenging due to polyploidy and long crossing cycles.

Targeted genome editing technology can potentially shorten the development of resistant citrus varieties. Using CRISPR/Cas9 technology, scientists from the University of Florida edited the canker susceptibility gene, CsLOB1, in Duncan grapefruit. Six independent lines, D_LOB2, D_LOB3, D_LOB9, D_LOB10, D_LOB11 and D_LOB12, were generated.

When inoculated with the canker pathogen Xanthomonas citri subsp. citri (Xcc), D_LOB2 and D_LOB3 showed symptoms similar to wild-type grapefruit. No canker symptoms were observed on D_LOB9, D_LOB10, D_LOB11 and D_LOB12 at 4 days after inoculation.

Pustules caused by Xcc were also observed on D_LOB9, D_LOB10, D_LOB11 and D_LOB12 in later stages, but were significantly less compared to pustules in wildtypes. Furthermore, the pustules on D_LOB9 and D_LOB10 did not develop into typical canker symptoms.

No side effects or off-target mutations were detected in the mutated plants.

For more information, read the full article in Plant Biotechnology Journal.