The Maize MID-COMPLEMENTING ACTIVITY Homolog CELL NUMBER REGULATOR13/NARROW ODD DWARF Coordinates Organ Growth and Tissue Patterning

Abstract

Organogenesis occurs through cell division, expansion, and differentiation. How these cellular processes are coordinated remains elusive. The maize (<i>Zea mays</i>) leaf provides a robust system to study cellular differentiation due to its distinct tissues and cell types. The <i>narrow odd dwarf</i> (<i>nod</i>) mutant displays defects at both the cellular and tissue level that increase in severity throughout growth. <i>nod</i> mutant leaves have reduced size due to fewer and smaller cells compared with the wild type. The juvenile-to-adult transition is delayed, and proximal distal-patterning is abnormal in this mutant. Differentiation of specialized cells such as those forming stomata and trichomes is incomplete. Analysis of <i>nod-1</i> sectors suggests that NOD plays a cell-autonomous function in the leaf. We cloned <i>nod</i> positionally and found that it encodes CELL NUMBER REGULATOR13 (CNR13), the maize MID-COMPLEMENTING ACTIVITY homolog. CNR13/NOD is localized to the membrane and is enriched in dividing tissues. Transcriptome analysis of <i>nod</i> mutants revealed overrepresentation of cell wall, hormone metabolism, and defense gene categories. We propose that NOD coordinates cell activity in response to intrinsic and extrinsic cues.