Functional Characterization of OsWRKY7, a Novel WRKY Transcription Factor in Rice

Transcription factors (TFs) orchestrate plant growth and development, yet the functional landscape of many TF gene families remains incomplete. Here, we systematically characterize OsWRKY7, an unannotated WRKY TF in rice. Phylogenomic analyses revealed that the WRKY7 subfamily originated in basal angiosperms and evolved under strong purifying selection. We demonstrate OsWRKY7 functions as a WRKY transcriptional activator, with its activity uniquely encoded within the N-terminal domain—a distinctive mechanism among WRKY proteins. The promoter is enriched with cis-elements responsive to hormone and stress signaling, and the gene shows predominant expression in seeds. Strikingly, haplotype analysis revealed exceptionally low genetic diversity at the OsWRKY7 locus, suggesting evolutionary constraint or a recent selective sweep. Our findings establish OsWRKY7 as a conserved regulator with unique molecular features, specifically the WRKY domain, providing a strategic target for both fundamental research and crop improvement.