Genome editing of the disease susceptibility gene CsLOB1 in citrus confers resistance to citrus canker.

ABSTRACT: Citrus is a highly valued tree crop worldwide, while, at the same time, citrus production faces many biotic challenges, including bacterial canker and Huanglongbing (HLB). Breeding for disease-resistant varieties is the most efficient and sustainable approach to control plant diseases. Traditional breeding of citrus varieties is challenging due to multiple limitations, including polyploidy, polyembryony, extended juvenility and long crossing cycles. Targeted genome editing technology has the potential to shorten varietal development for some traits, including disease resistance. Here, we used CRISPR/Cas9/sgRNA technology to modify the canker susceptibility gene CsLOB1 in Duncan grapefruit. Six independent lines, D_LOB 2, D_LOB 3, D_LOB 9, D_LOB 10, D_LOB 11 and D_LOB 12, were generated. Targeted next-generation sequencing of the six lines showed the mutation rate was 31.58%, 23.80%, 89.36%, 88.79%, 46.91% and 51.12% for D_LOB 2, D_LOB 3, D_LOB 9, D_LOB 10, D_LOB 11 and D_LOB 12, respectively, of the cells in each line. D_LOB 2 and D_LOB 3 showed canker symptoms similar to wild-type grapefruit, when inoculated with the pathogen Xanthomonas citri subsp. citri (Xcc). No canker symptoms were observed on D_LOB 9, D_LOB 10, D_LOB 11 and D_LOB 12 at 4 days postinoculation (DPI) with Xcc. Pustules caused by Xcc were observed on D_LOB 9, D_LOB 10, D_LOB 11 and D_LOB 12 in later stages, which were much reduced compared to that on wild-type grapefruit. The pustules on D_LOB 9 and D_LOB 10 did not develop into typical canker symptoms. No side effects and off-target mutations were detected in the mutated plants. This study indicates that genome editing using CRISPR technology will provide a promising pathway to generate disease-resistant citrus varieties.

SUBMITTER: Jia H 

PROVIDER: S-EPMC5466436 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature