KANG, JULIE* and NANCY G. DENGLER. Department of Botany, University of Toronto, 25 Willcocks St., Toronto, ON., M5S 3B2. - Cell cycling frequency and expression of the homeobox gene ATHB-8 during leaf vein development in Arabidopsis.
The histogenetic aspects of plant development depend on regulation of
cell division plane, timing and frequency to produce cell units of
correct size and shape for mature function. Differences among the
dermal, ground and vascular tissue systems arise during development,
largely through regulation of these aspects of cell cycling in
relation to overall tissue expansion. Using a cyclin1At::GUS
reporter construct, we demonstrate quantitative differences in cell
cycling frequency among tissue systems and among primary, secondary,
and tertiary veins; these differences are superimposed upon the more
general longitudinal gradient of cell division frequency in developing
leaves of Arabidopsis thaliana. Patterns of cell cycling
frequency coincide almost exactly with those of the earliest known
molecular marker of procambial identity, the HD-ZIP class III homeobox
gene ATHB-8, suggesting that ATHB-8 may play a role in
regulating the early events of procambial development, including
procambium-specific patterns of cell cycling.
Key words: Arabidopsis thaliana homeobox gene-8, Arabidopsis, cell cycle, leaf development, procambium, vein pattern