An inducible CRISPR activation tool for accelerating plant regeneration

The inducible CRISPR-activation (CRISPR-a) system offers unparalleled precision and versatility for regulating endogenous genes, making it highly sought after in plant research. In this study, we developed a plant chemically inducible CRISPR-a tool called ER-Tag by combining the XVE inducible system with the SunTag CRISPR-a system. We systematically compared different induction strategies and achieved high efficiency in target gene activation. We demonstrated that guide RNAs could be multiplexed and pooled for large-scale screening of effective morphogenic genes and gene pairs involved in plant regeneration. Further experiments showed that induced activation of these morphogenic genes accelerated regeneration and improved regeneration efficiency in both eudicot and monocot plants, including alfalfa, woodland strawberry and sheepgrass. Our study expanded the CRISPR toolset in plants and provided a powerful new strategy for studying gene functions when constitutive expression is not feasible or ideal.