The prokaryote-derived CRISPR–Cas genome editing technology has altered plant molecular biology beyond all expectations. Characterized by robustness and high target specificity and programmability, CRISPR–Cas allows precise genetic manipulation of crop species, which provides the opportunity to create germplasms with beneficial traits and to develop novel, more sustainable agricultural systems. Furthermore, the numerous emerging biotechnologies based on CRISPR–Cas platforms have expanded the toolbox of fundamental research and plant synthetic biology. In this Review, we first briefly describe gene editing by CRISPR–Cas, focusing on the newest, precise gene editing technologies such as base editing and prime editing. We then discuss the most important applications of CRISPR–Cas in increasing plant yield, quality, disease resistance and herbicide resistance, breeding and accelerated domestication. We also highlight the most recent breakthroughs in CRISPR–Cas-related plant biotechnologies, including CRISPR–Cas reagent delivery, gene regulation, multiplexed gene editing and mutagenesis and directed evolution technologies. Finally, we discuss prospective applications of this game-changing technology. The newest CRISPR–Cas genome editing technologies enable precise and simplified formation of crops with increased yield, quality, disease resistance and herbicide resistance, as well as accelerated domestication. Recent breakthroughs in CRISPR–Cas plant biotechnologies improve reagent delivery, gene regulation, multiplexed gene editing and directed evolution.

Applications of CRISPR–Cas in agriculture and plant biotechnology

Genome engineering for crop improvement and future agriculture

The development of CRISPR–Cas systems has sparked a genome editing revolution in plant genetics and breeding. These sequence-specific RNA-guided nucleases can induce DNA double-stranded breaks, resulting in mutations by imprecise non-homologous end joining (NHEJ) repair or precise DNA sequence replacement by homology-directed repair (HDR). However, HDR is highly inefficient in many plant species, which has greatly limited precise genome editing in plants. To fill the vital gap in precision editing, base editing and prime editing technologies have recently been developed and demonstrated in numerous plant species. These technologies, which are mainly based on Cas9 nickases, can introduce precise changes into the target genome at a single-base resolution. This Review provides a timely overview of the current status of base editors and prime editors in plants, covering both technological developments and biological applications. This Review summarizes the current status of base editors and prime editors in plants, reporting both technological developments and biological applications of these precise genome editors.

Precise plant genome editing using base editors and prime editors.

The CRISPR-Cas toolbox and gene editing technologies

CRISPR-Mediated Engineering across the Central Dogma in Plant Biology for Basic Research and Crop Improvement

Short insertions and deletions can be produced in plant genomes using CRISPR-Cas editors, but reliable production of larger deletions in specific target sites has proven difficult to achieve We report the development of a series of APOBEC-Cas9 fusion-induced deletion systems (AFIDs) that combine Cas9 with human APOBEC3A (A3A), uracil DNA-glucosidase and apurinic or apyrimidinic site lyase In rice and wheat, AFID-3 generated deletions from 5'-deaminated C bases to the Cas9-cleavage site Approximately one-third of deletions produced using AFID-3 in rice and wheat protoplasts (302%) and regenerated plants (348%) were predictable We show that eAFID-3, in which the A3A in AFID-3 is replaced with truncated APOBEC3B (A3Bctd), produced more uniform deletions from the preferred TC motif to the double-strand break AFIDs could be applied to study regulatory regions and protein domains to improve crop plants

Precise, predictable multi-nucleotide deletions in rice and wheat using APOBEC-Cas9.

Genome editing in plants with MAD7 nuclease.

The CRISPR/Cas9 based prime editing (PE) technique enables all 12 types of base substitutions and precise small DNA deletions or insertions without generating DNA double-strand breaks. Prime editing has been successfully applied in plants and plays important roles in plant precision breeding. Although plant prime editing (PPE) can substantially expand the scope and capabilities of precise genome editing in plants, its editing efficiency still needs to be further improved. Here, we review the development of PPE technique, and introduce structural composition, advantages and limitations of PPE. Strategies to improve the PPE editing efficiency, including the Tm-directed PBS length design, the RT template length, the dual-pegRNA strategy, the PlantPegDesigner website, and the strategies for optimizing the target proteins of PPE, were highlighted. Finally, the prospects of future development and application of PPE were discussed.

Dandan Zhang

Papers

Precise, predictable multi-nucleotide deletions in rice and wheat using APOBEC-Cas9.

Genome editing in plants with MAD7 nuclease.

[Plant prime editing technique: a new genome editing tool for plants].

Being tough: the secret weapon of plants against vascular pathogens.