Developmental and Structural Section
Ambrose, Barbara , Vasco, Alejandra , Smalls, Tynisha , Moran, Robbin .
Fern leaf evolution and development.
The evolution and development of leaves in land plants has been of great interest to botanists for decades. The microphylls of lycophytes and the megaphylls of ferns and seed plants are considered to have arisen independently and not be homologous. Furthermore, megaphylls are proposed to have arisen at least 4 times independently and thus are not all homologous. In assessing the homology of leaves, molecular genetic and developmental studies have proven useful. Such studies have elucidated the control of leaf development in the flowering plants and given insight into microphyll development in lycophytes; however, comparable data is largely lacking for ferns. One aim of this research is to supply such data for ferns, thus contributing to a big question in systematic botany about the homology of leaves in vascular plants. As our study group we have chosen Elaphoglossum, one of the most species-rich genera of ferns. The nearly 600 species of Elaphoglossum are characterized by simple entire leaves. However there are three species with dissected leaves (E. peltatum, E. moorei, and E. tripartitum) that belong to a small monophyletic group: Elaphoglossum section Squamipedia. Moreover molecular phylogenetic analyses have recovered Bolbitis, a genus with mainly divided leaf species, as the sister genus of Elaphoglossum. These phylogenetic hypotheses suggest that the simple, entire leaves typical of Elaphoglossum represent a derived state among dryopteroid ferns, and that the dissected leaves of the three species in sect. Squamipedia might represent a reversion to the divided condition. These natural variants of leaf shape will allow us to compare the expression of leaf development genes and determine whether changes in gene expression correlate with changes in leaf shape. The developmental data collected would be analyzed within a phylogenetic framework, and furthermore could be compared to what is known about development and gene expression in the leaves of seed plants and lycophytes, thus contributing a piece to the comparative puzzle about the homology of land plant leaves.
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1 - The New York Botanical Garden, 200th St. & Southern Blvd., Bronx, NY, 10458, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 551A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 10:30 AM