Induction of leaves directly from leaves in the maize mutant Lax midrib1-O

Dev Biol. 1997 Jun 1;186(1):36-45. doi: 10.1006/dbio.1997.8579.


One of the several phenes specified by the maize dominant mutation Lax midrib1-O (Lxm1-O on 3L) is the proliferation of leaf "flaps" usually paired around veins on the abaxial leaf surface. Using histology and scanning electron microscopy, we show these flaps to be authentic leaf structures; in rare instances, complete ectopic leaves are found. The first divisions preceding flap emergence occur between plastochrons 4 and 7, stages when the course of leaf differentiation is well under way. No sign of meristem or any small, densely cytoplasmic primordium-like cells were seen at the sites of flap initiation. In addition, the sites of ectopic leaf initiation do not express KNOX (Knotted-like homeobox) proteins, a molecular marker for shoot apical meristem cell identity. Thus, the cells that proliferate into ectopic leaves do not arise from a meristem or a primordium. A similar phenomenon has been described in several dicots, but in no other monocots. The details of flap morphology compared to the morphology of the leaf proper suggest a model whereby cells in regions of the leaf proper maintain the competence they acquired in the meristem. These cells then respond properly, in a regulated manner, to a delayed signal emanating from veins denoting "make the organ you are competent to make."

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Meristem / cytology
  • Meristem / growth & development*
  • Microscopy, Electron, Scanning
  • Morphogenesis
  • Mutation
  • Phenotype
  • Plant Leaves / growth & development*
  • Plant Leaves / ultrastructure
  • Zea mays / genetics*