AOBPreview originally published online on November 10, 2006
Annals of Botany 2007 99(1):53-60; doi:10.1093/aob/mcl238
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Generational Differences in Response to Desiccation Stress in the Desert Moss Tortula inermis
1 School of Life Sciences, University of Nevada, 4505 Maryland Parkway, Las Vegas, NV 89154-4004, USA
2 US Department of Agriculture, 205 Curtis Hall, University of Missouri, Columbia, MO 65211, USA
3 Department of Integrative Biology, 1001 Valley Life Sciences Bld, #2465, University of California, Berkeley, CA 94720-2465, USA
4 Department of Biology, 101 Morgan Bld, University of Kentucky, Lexington, KY 40506-0225, USA
* For correspondence. E-mail: LRS{at}UNLV.nevada.edu
Received: 15 June 2006 Returned for revision: 30 August 2006 Accepted: 19 September 2006 Published electronically: 10 November 2006
BACKGROUND AND AIMS: Active growth in post-embryonic sporophytes of desert mosses is restricted to the cooler, wetter months. However, most desert mosses have perennial gametophytes. It is hypothesized that these life history patterns are due, in part, to a reduced desiccation tolerance for sporophytes relative to gametophytes.
METHODS: Gametophytes with attached post-embryonic sporophytes of Tortula inermis (early seta elongation phenophase) were exposed to two levels of desiccation stress, one rapid-dry cycle and two rapid-dry cycles, then moistened and allowed to recover, resume development, and/or regenerate for 35 d in a growth chamber.
KEY RESULTS: Gametophytes tolerated the desiccation treatments well, with 93 % survival through regenerated shoot buds and/or protonemata. At the high stress treatment, a significantly higher frequency of burned leaves and browned shoots occurred. Sporophytes were far more sensitive to desiccation stress, with only 23 % surviving after the low desiccation stress treatment, and 3 % surviving after the high desiccation stress treatment. While the timing of protonemal production and sporophytic phenophases was relatively unaffected by desiccation stress, shoots exposed to one rapid-dry cycle produced shoots more rapidly than shoots exposed to two rapid-dry cycles.
CONCLUSIONS: It is concluded that sporophytes of Tortula inermis are more sensitive to rapid drying than are maternal gametophytes, and that sporophyte abortion in response to desiccation results from either reduced desiccation tolerance of sporophytes relative to gametophytes, or from a termination of the sporophyte on the part of the gametophyte in response to stress.
Key words: Bryophyte, desiccation stress, regeneration, sporophyte, gametophyte, protonema, Tortula inermis
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