Bryological and Lichenological Section/ABLS
Stark, Lloyd R. , McLetchie, Nicholas .
A new eukaryotic record for upper thermal tolerance among adult organisms.
SURFACE soil temperatures in the Mojave Desert routinely reach 60-80C during spring and summer, and spike up to 140C during wildfires. In the dioecious moss Syntrichia caninervis, females were hypothesized to have a higher thermal tolerance than males. This prediction derives from the lower sexual reproduction expenditures of females relative to males in this species. Eight genotypes of each sex were collected and randomly assigned 4 replicate shoots to each of the dry thermal exposures of 80, 100, and 120C. The previous high for a 30-minute exposure by a eukaryotic adult organism was 110C. Shoot viability was assessed by attempting to regenerate the shoots in culture. Response variables included, after 56 days in culture, the degree of shoot tissue chlorosis (burning), resumption in growth of the shoot apical meristem, proliferation through basal and/or subtending shoot buds, production of protonemata, and production of protonemal shoots. After exposure to 120C, all 32 shoots of each sex were able to regenerate in culture, thus eclipsing the previous eukaryotic record. Significant chlorosis attended those shoots exposed to 120C compared with the lower thermal treatments. Following the thermal exposures, males and females tended to have similar regenerational responses of viability, tissue burning, and protonemal emergence times.
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1 - University of Nevada, Las Vegas, Department of Biological Sciences, 4505 Maryland Parkway, Las Vegas, Nevada, 89154-4004, USA
2 - University of Kentucky, Department of Biological Sciences, 101 Morgan Bld, Lexington, Kentucky, 40506-0225, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 304/Bell Memorial Union
Date: Monday, July 31st, 2006
Time: 1:45 PM