| Abstract Detail
Developmental and Structural Section Landrum, Vic [1]. Testing the water-stress hypothesis for wide-band tracheids in two morphological variants of the southern African succulent Anacampseros (Portulacaceae).. Wide-band tracheids (WBTs) are novel tracheids found in xylary and non-xylary tissues of leaves and stems of species in the South African genus Anacampseros (Portulacaceae), and have a characteristic wide secondary wall that intrudes into the cell lumen. Wide-band tracheids are able to collapse physically under dehydration and rehydrate without loss of function; thus, WBTs are hypothesized to have evolved as a response to water stress conditions. To test this hypothesis, water stress experiments were performed to see effects on WBT formation and development in seed-grown tissues of two morphs, Anacampseros rufescens, and A. ustulata. Tissues were harvested and processed at 30 and 60 days growth, and four cell traits (diameter, lumen diameter, wide-band thickness, and percent cell area occupied by the secondary wall) as well as number of wide-band tracheids were measured. Results show that water stress did affect the expression of WBTs in the broader-leaved A. rufescens, but not in the small-leaved A. ustulata. Water-stressed plants showed a statistically significant increase in wide-band area within A. rufescens; in WBT number, there was an increase of 2000% in the water stressed seedlings of A. rufescens (from Control to 15ml groups). Additional experiments showed that neither nutritional nor temperature stress affected WBT number/structure. Thus, WBT numbers increase in response to water stress. However, other experiments have shown that light intensity exposure also has an effect on WBT traits.
Log in to add this item to your schedule
1 - Washburn University, Biology, 1700 SW College Ave., Topeka, Kansas, 66621, USA
Keywords:
wide-band
tracheid
Anacampseros
Portulacaceae.
Presentation Type: Poster:Posters for Sections
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PDS001
Abstract ID:37 |
