Dessication Tolerance in Bryophytes and Lichens
Alpert, Peter .
The limits and frontiers of desiccation tolerance.
Drying to equilibrium with the air is lethal to most organisms, making drought a central problem for terrestrial life and a major cause of agronomic failure and human famine. Surprisingly, a wide taxonomic variety of plants, microbes, and animals do tolerate complete desiccation. Species in five phyla of animals and all major taxa of plants contain desiccation-tolerant adults, juveniles, seeds, or spores. There seem to be few inherent limits on desiccation tolerance, since tolerant organisms can survive extremely intense and prolonged desiccation. There seems to be little phylogenetic limitation of tolerance in plants but may be more in animals. Physical constraints may restrict tolerance to plants shorter than 3 m and animals without rigid skeletons. Physiological constraints on tolerance in plants may include control by hormones with multiple effects that could link tolerance to slow growth. Tolerance tends to be lower in organisms from wetter habitats, and there may be selection against tolerance when water availability is high. Our current knowledge of the limits to tolerance suggests that they pose few obstacles to inducing and engineering tolerance in prokaryotes and in isolated cells and tissues, and there has already been much success on this scientific frontier of desiccation tolerance. However, physical and physiological constraints may explain the comparative lack of success in extending tolerance to whole plants or animals. Deeper understanding of the limits to desiccation tolerance in living things may help us cross this next frontier.
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1 - University of Massachusetts, Biology, Amherst, Massachusetts, 01003, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Salon K - Austin Grand Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 8:45 AM