15
The Regulation of Dorsiventral
Symmetry in Plants
STEFAN GLEISSBERG 1 , MINSUNG KiM 2 , JUDY JERNSTEDT 3 , AND NEELIMA SINHA 2
1 Institute of Systematic Botany, University of Mainz, 55099 Mainz, Germany
2 Section of Plant Biology, University of California, Davis, CA 95616, USA
3 Department of Agronomy and Range Science, University of California, Davis, CA 95616,
USA
Abstract
The higher plant shoots are generally radially symmetrical; leaves produced at the
shoot apex are dorsiventral while axillary shoots again show radial symmetry. Recently analyzed mutants in different plants indicate that the proper definition of
adaxial and abaxial identities is necessary to generate a leaf margin and dorsiventral symmetry. Two genes important in the regulation of transsectionalleaf symmetry arc PHANTASTICA (a MYB (Myeloblastosis oncogene)-domain transcription
factor) and KNOTIEDl-like genes (homeodomain transcription factors). We review these results in light of hypotheses about the evolutionary origin of leaves and
discuss similarities of mutant phenotypes to unifacial leaves occurring in extant
taxa. Related symmetry phenomena of tlattened shoots and parallels to the acquisition of dorsal and ventral identities in Drosophila wing imaginal discs are pointed
out.
1 Introduction
The higher plant shoot system is generally radially symmetrical; leaves produced
on the shoot apex are bilaterally symmetrical while axillary shoots usually show
radial symmetry. In a developing leaf primordium sub-organ identities are delimited along three axes. Acquisition of characteristic features along these three axes
gives the leaf a shape peculiar to the species. This review will focus on the acquisiKey words. shoot and leaf development, radial symmetry, dorsiventrality, KNOX genes,
leaf evolution, PHANTAST/CA, leaf blades, abaxial, adaxial, KNOTTED, unifaciality,
homeobox genes, MYB domain, wing development, rough sheath 2
223
The Regulation of Dorsiventral
Symmetry in Plants
STEFAN GLEISSBERG 1 , MINSUNG KiM 2 , JUDY JERNSTEDT 3 , AND NEELIMA SINHA 2
1 Institute of Systematic Botany, University of Mainz, 55099 Mainz, Germany
2 Section of Plant Biology, University of California, Davis, CA 95616, USA
3 Department of Agronomy and Range Science, University of California, Davis, CA 95616,
USA
Abstract
The higher plant shoots are generally radially symmetrical; leaves produced at the
shoot apex are dorsiventral while axillary shoots again show radial symmetry. Recently analyzed mutants in different plants indicate that the proper definition of
adaxial and abaxial identities is necessary to generate a leaf margin and dorsiventral symmetry. Two genes important in the regulation of transsectionalleaf symmetry arc PHANTASTICA (a MYB (Myeloblastosis oncogene)-domain transcription
factor) and KNOTIEDl-like genes (homeodomain transcription factors). We review these results in light of hypotheses about the evolutionary origin of leaves and
discuss similarities of mutant phenotypes to unifacial leaves occurring in extant
taxa. Related symmetry phenomena of tlattened shoots and parallels to the acquisition of dorsal and ventral identities in Drosophila wing imaginal discs are pointed
out.
1 Introduction
The higher plant shoot system is generally radially symmetrical; leaves produced
on the shoot apex are bilaterally symmetrical while axillary shoots usually show
radial symmetry. In a developing leaf primordium sub-organ identities are delimited along three axes. Acquisition of characteristic features along these three axes
gives the leaf a shape peculiar to the species. This review will focus on the acquisiKey words. shoot and leaf development, radial symmetry, dorsiventrality, KNOX genes,
leaf evolution, PHANTAST/CA, leaf blades, abaxial, adaxial, KNOTTED, unifaciality,
homeobox genes, MYB domain, wing development, rough sheath 2
223