Optimized prime editing efficiently generates heritable mutations in maize

Low efficiency is the main obstacle to using prime editing in maize (Zea mays). Recently, prime-editing efficiency was greatly improved in mammalian cells and rice (Oryza sativa) plants by engineering prime-editing guide RNAs (pegRNAs), optimizing the prime editor (PE) protein, and manipulating cellular determinants of prime editing. In this study, we tested PEs optimized via these three strategies in maize. We demonstrated that the ePE5max system, composed of PEmax, epegRNAs (pegRNA-evopreQ. 1), nicking single guide RNAs (sgRNAs), and MLH1dn, efficiently generated heritable mutations that conferred resistance to herbicides that inhibit 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), acetolactate synthase (ALS), or acetyl CoA carboxylase (ACCase) activity. Collectively, we demonstrate that the ePE5max system has sufficient efficiency to generate heritable (homozygous or heterozygous) mutations in maize target genes and that the main obstacle to using PEs in maize has thus been removed.