Knockout of the Citrus CsLOB1 Gene Using CRISPR/Cas9 Confers Resistance to Citrus Canker

Citrus production around the world is susceptible to challenges including diseases such as bacterial canker and Huanglongbing (HLB). Breeding programs can address some of these challenges but suffer from long crossing cycles, extended juvenility, polyembyrony and last, but not the least, polyploidy. Use of gene-editing techniques hold promise that the obstacles created by polyploidy can be overcome and allow scientists to achieve pivotal changes in target genes in a relatively short period of time. Evidence that this can be the case is provided by the recent work of Jia et al.25 who used CRISPR/Cas9 technology to target the canker susceptibility gene, CsLOB1, of Duncan grapefruit for knockout. They achieved high rates of gene modification in most of the six independent knockout lines they created. Two of these lines showed significantly reduced infection with the citrus canker-causing pathogen Xanthomonas citri subsp. citri (Xcc) and the small pustules that developed on these plants did not develop into typical canker symptoms. Thus, the CRISPR/Cas9 system appears to hold great promise to help control and contain the spread of devastating crop diseases such as citrus canker. –