CRISPR-targeted transposable element insertion for efficient plant genome engineering

Abstract

The current technologies to place new DNA into specific locations in plant genomes are low frequency and error-prone, and this inefficiency hampers genome editing approaches to develop improved crops. Often considered genome ‘parasites’, transposable elements (TEs) evolved to insert their DNA seamlessly into genomes. TEs select their site of insertion based on preferences for chromatin contexts, which differ for each TE type. We developed a genome engineering tool that controls the TE insertion site and cargo delivered, taking advantage of the TE’s natural ability to precisely insert into the genome. Inspired by CRISPR-associated transposases (CASTs) that target transposition in a programmable manner in bacteria, we generated a synthetic CAST by fusing the rice Pong TE transposase protein to the Cas9 or CPF1 programmable nucleases. We demonstrated sequence-specific targeted delivery (guided by the CRISPR gRNA) of enhancer elements, an open reading frame and gene expression cassette into the genome of the model plant Arabidopsis. We additionally translated this system into soybean, a major global crop in need of targeted insertion technology. We have engineered a TE ‘parasite’ into a usable and accessible toolkit that enables the sequence-specific targeting of custom DNA into plant genomes.