Molecules to Morphology: Developing an Understanding of Plant Evolution Through Time
Sanders, Heather .
Physiological mechanisms of leaf shape in Ceratoperis.
While our knowledge of the developmental basis of morphology in angiosperms is extensive, we are lacking comparable information on morphogenesis in other vascular plant groups. Comparative studies of organogenesis in ferns and seed plants will differentiate homology from parallel evolution of form. As such, studies of leaf genetics, development and physiology in ferns have the potential to identify the developmental regulatory pathways that are the same as, or different from seed plant leaves. The fern Ceratopteris richardii is used as a model organism for genetic studies and is ideal for examining leaf morphogenesis in ferns because it has a heteroblastic series of leaf development. Leaves in C. richardii range from entire ovate leaves on sporelings, to highly lobed leaves produced on older rhizomes. This study examined the effect of auxin transport inhibitors on leaf morphogenesis in C. richardii to identify similarities and/or differences from effects on leaf morphology in seed plants. Auxin transport inhibitors, N-(1-Naphthyl) phthalamic acid (NPA) and 2-3-5-triiodobenzoic acid (TIBA) were applied to sporophytes of C. richardii. The sporophytes showed radical alterations in leaf morphology. In the plants that were treated with auxin transport inhibitors, leaves that were normally ovate became lanceolate, sometimes precociously lobed. These leaves had 1-2 vascular strands, in contrast to reticulate venation of normal leaves. Spatial alterations in auxin accumulation were correlated with morphological alterations. The morphological changes observed in C. richardii leaves were different from morphological changes in seed plant leaves that result from reductions in auxin transport, suggesting parallel evolution of leaf morphology.
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1 - Ohio University, Department of Environmental & Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
Evolution and Development.
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 5/Hilton
Date: Wednesday, July 11th, 2007
Time: 4:00 PM