Beyond knockouts: fine-tuning regulation of gene expression in plants with CRISPR-Cas-based promoter editing

The CRISPR-Cas-based genome editing field in plants is expanding rapidly. Editing plant promoters to obtain cis-regulatory alleles with altered expression levels or patterns of target genes is a highly promising topic. However, primarily used CRISPR-Cas9 has significant limitations when editing noncoding sequences like promoters, which have unique structures and regulatory mechanisms, including A-T richness, repetitive redundancy, difficulty in identifying key regulatory regions, and a higher frequency of DNA structure, epigenetic modification, and protein binding accessibility issues. Researchers urgently require efficient and feasible editing tools and strategies to address these obstacles, enhance promoter editing efficiency, increase diversity in promoter polymorphism, and, most importantly, enable 'non-silent' editing events that achieve precise target gene expression regulation. This article provides insights into the key challenges and references for implementing promoter editing-based research in plants.