Genome-wide identification and expression analysis of the maize ZmWOX gene family reveal its critical role in callus formation

WUS (WUSCHEL) is a homeobox transcription factor that serves as a key regulator in maintaining stem cells in an undifferentiated state. Plant stem cells possess the capacity for continuous division and differentiation, making them ideal recipients for genetic transformation. In this study, 24 ZmWOXs genes belonging to three subgroups (I-III) were identified in maize. Expression analysis of these genes across six callus time points (D0, D1, D2, D4, D6, D8) revealed their critical role in callus formation. Phylogenetic analysis resolved the family into three subgroups, and sequence inspection revealed a universally conserved homeodomain, predominant nuclear localization, and highly similar functional annotations for all encoded proteins. Promoter profiling showed an auxin- and meristem motif–rich cis-element landscape that is unevenly distributed among subgroups and underlies their divergent roles in callus differentiation. Time-course expression analysis uncovered six ZmWUS-like genes that are steadily up-regulated during callus induction; the four most highly expressed members represent ready-to-use endogenous morphogenic factors for rapidly boosting maize transformation efficiency. Taken together, our study delivers a genome-wide characterization of the maize ZmWOX gene family and establishes a solid foundation for exploiting ZmWOX members to boost maize genetic transformation.