The Functional Significance of Leaf Shape Variation - Towards a Consensus from Gene to Community
Gleissberg, Stefan .
Leaf marginal blastozones – a concept revisited after molecular evidence.
Investigations of the comparative morphogenesis of leaves in diverse taxa have identified the primordial leaf margin as a crucial element. Primary morphogenetic events such as leaflet and serration formation and marginal fusions all originate from primordial margins during an early phase of leaf growth. At the same time, several lines of evidence suggested that the traditional concept of marginal meristems as clonal origins of leaf blade tissue with enhanced mitotic activity may not be valid. The concept of leaf marginal blastozones, in contrast to marginal meristems, emphasizes a specific competence of primordial margins in primary morphogenesis, which appears to be maintained as long as histogenetic differentiation does not occur. It also suggests that a marginal blastozone already contributes to leaf initiation, so leaves are dorsiventral organs from the offset. Here, I am revisiting this concept, 11 years after it was proposed, under the light of developmental genetic evidence that has accumulated since. Molecular regulation of blastozone initiation and fusion, segment initiation, and the transition to histogenesis are discussed.
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1 - Ohio University, Environmental and Plant Biology, Porter Hall, Athens, Ohio, 45701, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Williford B/Hilton
Date: Monday, July 9th, 2007
Time: 10:15 AM