Dessication Tolerance in Bryophytes and Lichens
Stark, Lloyd R. .
Generational differences in desiccation tolerance in the moss Tortula inermis.
Shoots of Tortula inermis with sporophytes at the seta elongation phenophase (postembryonic yet prior to capsule expansion) were collected from the Mojave Desert following a series of rain events in December 2004 and allowed to air-dry slowly. In order to test the hypothesis that gametophytes are more desiccation tolerant than sporophytes, individual shoots of Tortula that each had an immature sporophyte were subjected to the following treatments: control (0 rapid-dry cycles), 1 rapid-dry cycle, and 2 consecutive rapid-dry cycles (N=30 each treatment). A rapid-dry (RD) cycle consisted of a prehydration period of 60 min followed by blotting and desiccation of shoots/sporophytes at 15% RH, ensuring desiccation in <30 min. Shoots were then hydrated, transferred upright onto sand in petri dishes, and allowed to resume growth and/or regenerate for 35 days. Protonemal, shoot, and sporophyte maturation were monitored. In the high stress treatment (2 RD cycles) 23 of 30 gametophytes regenerated by either producing protonemata or shoot buds, whereas only one of 30 sporophytes matured to meiosis (29 sporophytes aborted). In the low stress treatment (1 RD cycle), 30 of 30 gametophytes regenerated and 7 of 30 sporophytes resumed growth and reached meiosis (23 sporophytes aborted). In the control treatment (0 RD cycles), 30 of 30 gametophytes regenerated and 22 of 30 sporophytes reached meiosis (8 sporophytes aborted). Sporophytes were therefore less able to tolerate rapid desiccation than gametophytes. Also consistent with these results is an alternative hypothesis that under high stress conditions, gametophytes control and may terminate sporophyte development.
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1 - University of Nevada, Department of Biological Sciences, 4505 Maryland Parkway, Las Vegas, Nevada, 89154
Presentation Type: Symposium or Colloquium Presentation
Location: Salon K - Austin Grand Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 2:30 PM