title: The maize milkweed pod1 mutant reveals a mechanism to modify organ morphology.
abstract: Plant lateral organs, such as leaves, have three primary axes of growth-proximal-distal, medial--lateral and adaxial-abaxial (dorsal-ventral). Although most leaves are planar, modified leaf forms, such as the bikeeled grass prophyll, can be found in nature. A detailed examination of normal prophyll development indicates that polarity is established differently in the keels than in other parts of the prophyll. Analysis of the maize HD-ZIPIII gene rolled leaf1 (rld1) suggests that altered expression patterns are responsible for keel outgrowth. Recessive mutations in the maize (Zea mays) KANADI (KAN) gene milkweed pod1 (mwp1), which promotes abaxial cell identity, strongly affect development of the prophyll and silks (fused carpels). The prophyll is reduced to two unfused midribs and the silks are narrow and misshapen. Our data indicate that the prophyll and other fused organs are particularly sensitive to disruptions in adaxial-abaxial polarity. In addition, lateral and proximal-distal growth of most lateral organs is reduced in the mwp1-R mutant, supporting a role for the adaxial-abaxial boundary in promoting growth along both axes. We propose that the adaxial-abaxial patterning mechanism has been co-opted during evolution to generate diverse organ morphologies.
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York, USA.
authors.forename: Robyn
authors.initials: R
authors.lastname: Johnston
authors.forename: Héctor
authors.initials: H
authors.lastname: Candela
authors.forename: Sarah
authors.initials: S
authors.lastname: Hake
authors.forename: Toshi
authors.initials: T
authors.lastname: Foster
mesh_terms: D016764:Cell Polarity; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D003313:Zea mays / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development
chemical_list: D010940:Plant Proteins