The YPEL gene <i>CELL DIVISION SUPPRESSOR</i> negatively regulates cell division in plants

The <i>CELL DIVISION SUPPRESSOR</i> (<i>CDS</i>) gene encodes a conserved YPEL-family zinc-finger protein whose biological role in plants has remained largely uncharacterized. Here, we characterized the <i>Arabidopsis CDS</i> gene and demonstrated that its protein contains a conserved metal-binding motif and a canonical nuclear localization sequence shared across YPEL proteins. Although <i>CDS</i> mRNA is constitutively expressed in all tissues, promoter-reporter analyses revealed that CDS protein accumulates only weakly and is absent in meristematic cells, suggesting strong posttranscriptional regulation. Overexpression of <i>CDS</i> (35S::<i>CDS</i>) caused severe growth inhibition, disrupted root meristem organization, reduced cell number, enlarged cell size, and decreased CYCB1;1 activity, indicating that elevated <i>CDS</i> suppresses mitotic progression and promotes entry into the endocycle. A <i>Phalaenopsis</i> ortholog, <i>PaCDS</i>, displayed similar expression patterns and recapitulated the <i>Arabidopsis</i> overexpression phenotypes, demonstrating evolutionary conservation of <i>CDS</i> function across monocots and dicots. Subcellular localization analysis showed that CDS enters the nucleus specifically in dividing cells and associates with DNA during mitosis. Together, these findings reveal CDS as a conserved negative regulator of cell division that modulates meristem activity by repressing the mitotic cell cycle and promoting endocycle initiation. This work uncovers a previously unrecognized role of YPEL-family proteins in plant cell cycle control and provides a foundation for manipulating growth and organ development across species.