Specific and heritable gene editing in Arabidopsis

Abstract

Targeted gene editing could offer tremendous advantages over traditional plant breeding to create new cultivars with advantageous combinations of alleles, especially when stacking of important traits is needed for crop improvement. Traditional methods of combining desirable alleles of different genes involve time-consuming crosses and selections, and in some cases such as combining closely linked loci, traditional methods are impossible to implement. The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) relies on a small guide RNA (gRNA) molecule to direct specific cleavages of DNA sequences, and it has been widely tested for targeted gene editing in many organisms including plant species such as Arabidopsis, sorghum, rice, wheat, and tobacco. CRISPR/Cas can potentially be used to directly and precisely modify genes in the top commercial crop lines within a short period without affecting the existing valuable traits. However, before CRISPR/Cas can be widely used for crop improvement, several fundamental questions need to be addressed. What types of mutations can the CRISPR/Cas system generate in plants? Are the edited genomes stable and heritable? How often does unintended off-target mutagenesis occur and how do we decrease the off-target effects? In PNAS, Feng et al. (1) report a detailed analysis of CRISPR/Cas-mediated gene editing in Arabidopsis to address the aforementioned questions by following several generations of transgenic plants that harbor the CRISPR/Cas system, which was introduced into Arabidopsis by agrobacteria-mediated transformation. They studied seven genes at 12 distinct target sites to elucidate the pattern, specificity, and heritability of mutations induced by CRISPR/Cas. They clearly demonstrated that CRISPR/Cas could be used to generate transgene-free Arabidopsis plants with specific and heritable mutations within two generations (Fig. 1).