Choinski, John S. Jr. .
Photosynthesis and heat resistance in immature leaves of Weinmannia racemosa.
Numerous studies have examined how changing leaf temperature affects photosynthesis, but few have investigated the role of leaf development in that interaction. This report will show that immature leaves (~18% of final leaf area) of the common New Zealand tree, Weinmannia racemosa are less sensitive to rapid changes in leaf temperature (from 25 to 35ºC) as measured by chlorophyll a fluorescence and photosynthetic gas exchange than are developed leaves. Relative differences in the resistance of photosystem II to heat were supported by solute leakage experiments, in which disks from immature leaves incubated at 47ºC lost significantly fewer solutes than did disks from mature leaves. Also, lipid analysis showed that developing leaves had far lower levels of trienoic (18:3) fatty acids than did mature leaves. It is concluded that differences in photosynthetic tolerance to heat stress are based on developmental changes in the composition of the thylakoid membrane occurring during leaf expansion. This result may be useful in modeling temperature responses to photosynthesis, particularly under extreme conditions when leaf temperatures are high or rapidly fluctuate.
Log in to add this item to your schedule
1 - University of Central Arkansas, Biology, Conway, AR, 72035, USA
trienoic fatty acids
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM