Recently, scientists from the University of Tsukuba developed a novel CRISPR/Cas9-based genome-editing tool called Target activation-induced cytidine deaminase (Target-AID). They targeted SlDELLA and SlETR in the model tomato cultivar "Micro-Tom' and in commercial tomato cultivars to confirm and extend the applicability of the Target-AID genome-editing system.

After confirming that nucleotide substitutions were induced by the Target-AID system, mutants that showed high GA sensitivity in both "Micro-Tom' and the commercial cultivars were isolated. Nucleotide substitution was also successfully induced by multi-targeting with a single sgRNA and multi-targeting with multiple sgRNAs in a single vector. In addition, the Target-AID system also produced a Target-AID-specific pattern of indels with editing positions different from those of Cas9 vectors.

"We demonstrate that the Target-AID system could efficiently edit sgRNA-targeting sites and facilitate a case study on the application of base-editing technology to translational research that aims at the commercialization of genome-edited crops," Prof Ezura said. These results demonstrated that the Target-AID genome-editing system is a promising tool for molecular breeding in tomato crops, highlighting the scientific and agricultural potential of the combined use of Target-AID with other base-editing systems.

The research was published in Horticulture Research.