Bryological and Lichenological Section/ABLS
Schuette, Scott , Renzaglia, Karen S. , Duckett, Jeffrey G. .
Exploring the biology of the model moss Physcomitrella patens: the forgotten frontier.
FOLLOWING the discovery of homologous recombination in Physcomitrella, a wave of mutagenesis studies has led to the identification of the effects of a wide range of gene product on the moss phenotype. Lagging far behind these molecular advances is the understanding of the biology of this moss in nature and we remain ignorant about many basic features of its morphogenesis. Wild and cultured protonemata of Physcomitrella are remarkably similar. Both lack any kind of asexual propagules, but with ageing, the chloronemata dedifferentiate into brood cells. In common with many ephemeral mosses, the chloronemal system fails to develop further following gametophore initiation. Whereas chloronemata grow by intercalary expansion, caulonemata and rhizoids extend by tip growth. Differentiation of caulonemata involves major changes in the cell walls and cytoplasmic organization, many of these mirroring those in food-conducting leptoids. Embryogenesis follows a similar pattern to other bryopsid mosses and the placenta has wall ingrowths in both generations. The spore walls have a thin distal exine and a thicker intine that is greatly expanded proximally into an aperture. Pectin occurs in the walls of both the spore mother cells and in the intine of mature spores. The high lipid content of the mature spores is associated with extreme longevity in ephemeral habitats.
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1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA
2 - Queen Mary, University of London, School of Biological Sciences, London, E1 4NS, United Kingdom
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 9:30 AM