Poster: Temperature Responses

Abs # 203: Protein synthesis elongation factors, EF-Tu and EF1a, and plant thermo-tolerance

Presenter:	Ristic, Zoran , zristic@usd.edu
Authors	Ristic, Zoran  (A)   Gall, Valerie  (A)   Yost, Ross  (A)   Taecker, Mathew  (A)
Affiliations:	(A): The University of South Dakota

Chloroplast protein synthesis elongation factor EF-Tu and its homologous cytoplasmic counterpart EF-1á are proteins that play a pivotal role in the translational process of protein synthesis. Recent studies, however, have revealed that EF-Tu has additional functions that are related to plant tolerance to heat stress [Bhadula et al. (2001) Planta 212: 359-366; Moriarty et al. (2002) Plant Sci. 163: 1075-1082]. This protein has been found to play a role in the development of heat tolerance possibly by acting as a molecular chaperone [Moriarty et al. (2002) Plant Sci. 163: 1075-1082]. EF-Tu shows some similarity to EF-1á, and we speculate that EF-1á may also have functions related to plant tolerance to heat stress. Our goal is to investigate this possibility. As a step in reaching this goal, we studied the relative levels of EF-1á in a heat tolerant, ZPBL 1304, and a heat sensitive, ZPL 389, maize lines under high temperature stress conditions (45°C). In addition, we also investigated the relative levels of EF-Tu and EF-1á in these two lines under chilling conditions (8°C - 14°C). We used western blotting and immuno-gold labeling coupled with transmission electron microscopy. The preliminary results showed that the more stress tolerant ZPBL 1304 had higher levels of EF-Tu and EF-1á than the less tolerant ZPL 389. The levels of EF-Tu and EF-1á increased in both lines under both heat and chilling conditions indicating possible involvement of these proteins in plant response to thermal stress.