De novo Genes in Plants: Origins, Mechanisms, and Functional Implications

De novo genes originate from previously non-coding genomic regions. They provide an important source of lineage-specific innovation. In plants, these genes may contribute to adaptation, trait diversity and crop evolution. This review summarizes recent progress in plant de novo gene research. It first discusses major routes of gene birth, including transcription-first, open reading frame (ORF)-first and concurrent models. It also examines how nascent loci acquire regulatory control and enter existing biological networks. The review then summarizes their evolutionary features, including weak early constraint, rapid molecular change, restricted expression and structural refinement. It further discusses plant de novo genes involved in stress responses, seed germination, kernel dehydration, subspecies divergence, reproductive isolation and floral scent diversification. Current methods for identifying de novo genes remain limited by rapid sequence evolution, genome annotation quality, polyploidy and transposable elements. Whole-genome synteny alignment, multi-omics evidence and machine-learning approaches can improve candidate discovery. However, each method has important limitations. Finally, this review highlights key future questions in functional validation, latent coding potential in long non-coding RNAs, epigenetic activation, regulatory-network integration and crop improvement. These perspectives clarify how de novo genes shape plant adaptation and how they may be used in precision breeding and synthetic biology.