Regulatory Genes in Plant Development: Homeobox

Abstract Over the past 25 years, numerous homeobox genes have been identified and their functions have been elucidated. Many studies in various plant species have revealed that Knotted‐like homeobox ( KNOX ) genes, the first identified homeobox gene in plants, play a profound role in shoot apical meristem organisation, maintenance, and leaf initiation. In addition to the KNOX gene, numerous other homeobox genes have been discovered (e.g., BEL1‐like homeodomain , Homeodomain leucine zipper , and WUSCHEL‐related homeobox genes) and play important roles in plant development. Moreover, in recent years, it has become clear that the homeobox genes also contribute to morphological diversity in plants. Key Concepts Homeobox (HB) genes encode a subset of transcription factors that contain a homeodomain In plants, several groups of HB genes (e.g., KNOTTED‐like homeobox , BEL1‐like homeodomain , Homeodomain leucine zipper , and WUSCHEL‐related homeobox genes) have been shown to have a distinct role in the development. The HB genes are involved in a wide range of developmental processes (e.g., stem cell maintenance in the SAM and floral meristems, cambium, and root meristem, leaf development, vascular development, embryo patterning, etc.). Recent studies revealed that changes in HB genes led to leaf form diversification and that HB genes are involved in alteration in response to environmental changes in a single plant.