Mechanisms and applications of epigenome editing in plants: current status, challenges and future perspectives

Epigenome editing has become a leading-edge technology of programmable, heritable and reversible control of gene expression in plants without changing the DNA sequence. CRISPR/dCas9 systems along with transcription activator-like effectors (TALEs) and zinc finger systems have made it possible to manipulate DNA methylation, histone modifications, and RNA epigenetic marks in a precise and locus-specific fashion. These tools have been used on major regulatory genes of flowering time, stress adjustment, and yield maximization in model and crop plants. This review synthesizes the current status of plant epigenome editing advances and highlights mechanistic innovations including SunTag, CRISPRoff/on and RNA m6A editing. It also emphasizes new paradigm shifts in chromatin reprogramming, including transcription-resistive chromatin states, locus-specific H3K27me3 demethylation, and nanobody-mediated chromatin targeting. Furthermore, it considers the consequences of these shifts in the context of trait stability and epigenetic inheritance. Moreover, the relative evaluation of dCas9-, TALE-, and ZFP-based platforms indicated that there are still enduring problems in the performance of delivery, off-target effects, and transgenerational stability. The review concludes with a conceptual framework connecting epigenome editing to climate-smart crop improvement and outlines future research priorities focused on combinatorial multi-omics integration and the development of environmentally responsive editing platforms.