PARENT SESSION
Posters P5D Emerging techniques and systems. Abstracts (731-741)

Developing ECS-based methods for probing proton motive force. Jeffrey Cruz^*,1, Thomas Avenson¹, Kenji Takizawa¹, Atsuko Kanazawa¹, David Kramer¹, ¹ Washington State University, Pullman, WA, USA

ABSTRACT- The electrochromic shift (ECS), as first described by Junge and Witt (1968), is a shift in the absorbance spectrum of pigments embedded in the thylakoid membrane, induced by the formation of a transthylakoid electric field (). Uncertainties in calibration have limited its use as a direct measure of proton motive force (pmf) in intact leaves. However, recent developments in instrumentation have expanded the repertoire of ECS-based kinetic and analytical techniques for study of pmf and related processes. Variations of Dark Interval Relaxation Kinetics (DIRK) can yield information on how pmf may change in relation to proton conductivity or to its differential partitioning into and pH, under conditions of stress. In combination with other spectroscopic tools such as chlorophyll a fluorescence, ECS-based methods have expanded our understanding of the relationships among linear electron flux (LEF), pmf and down regulation. These same methods can be applied to the identification and characterization of mutants with defects in pmf formation or partitioning.

KEY WORDS: proton motive force, electrochromic shift, spectroscopy