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Dessication Tolerance in Bryophytes and Lichens

Mishler, Brent D. [1].

The evolution and ecology of desiccation tolerance in mosses.

The conquest of land by plants was clearly one of the most important events in the history of the earth, because it prepared the way for the development of terrestrial food chains and thus the movement of other lineages onto land, including tetrapods and insects. Bryophytes and tracheophytes adopted very different approaches to being a land plant; in general the bryophytes differ in most ways in their biology, ecology, and evolution from tracheophytes. One major difference is poikilohydry (the rapid equilibration of the plants water content to that of the surrounding environment) and desiccation tolerance (the ability of a plant to recover after being air-dry at the cellular level. Phylogenetic analyses suggest that desiccation tolerance was primitively present in the bryophytes (the basal-most living land plants), but has been lost in the evolution of tracheophytes. All bryophytes have these abilities to some extent, but they were lost in the elaboration of the larger, more complex, and endohydric trachephytes, possibly because of trade-offs between productivity and the resources needed for desiccation tolerance. Desiccation tolerance has re-evolved in seeds and pollen and vegetatively in Selaginella, the ferns, and at least eight independent evolutions in the angiosperms. The moss Tortula ruralis is the best studied bryophyte -- Oliver and colleagues have identified several genes that appear to be intimately involved in desiccation tolerance. We are using comparative genomic approaches to find homologs among species of the Tortula ruralis complex and between bryophyte groups and the tracheophyte lineages. In particular we are targeting the exemplar species identified by the Deep Green collaboration in a synthesis of a reconstructed phylogenetic tree for all land plants. We are also using remote sensing and laboratory physiology studies to better understand the ecological context in which these mosses live.


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Related Links:
The Moss Cam site
The Green Tree of Life site
Plants Without Water


1 - University of California, Berkeley, Department of Integrative Biology, 1001 Valley Life Sciences Bldg. #2465, Berkeley, California, 94720-2465, USA

Keywords:
desiccation tolerance
bryophytes
mosses
land plants.

Presentation Type: Symposium or Colloquium Presentation
Session: 27-6
Location: Salon K - Austin Grand Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 11:15 AM
Abstract ID:487


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