Poster: Tropisms
Abs #
670: Characterization of Light-Induced Chloroplast Movement in Arabidopsis
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Presenter: |
Luesse, Darron R., dluesse@bio.indiana.edu |
Authors | Luesse, Darron R. (A) Deblasio, Stacy (A) Mullen, Jack (A) Hangarter, Roger P. (A) | | Affiliations: |
(A): Indiana University
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The optimization of photosynthesis is critical for a plant to thrive. While a plant can do little to alter the amount of light to which it is exposed, movement of chloroplasts allows alterations of the amount of light the photosynthetic machinery itself absorbs. Under low fluence rates, chloroplasts accumulate along the periclinal cell walls (top and bottom, or face position) and under high fluence rates, the chloroplasts migrate to anticlinal cell walls (sides, or profile position). It is hypothesized that chloroplasts move to the face position under low fluence rates to maximize light capture, and to the profile position under high fluence rates to avoid photodamage. The mechanism of this movement is not well understood, although treatments with the actin depolymerizing compound cytochalasin D indicate it is actin based. The goal of this research is to better understand the mechanisms that control light-induced chloroplast movement. A mutant screen designed to isolate lines with altered chloroplast movement has been effective. Progress with cloning and characterization of a high light defective mutant, designated pmi2 (Plastid Movement Impaired) will be presented, along with the characterization of the chloroplast movement response in the mutant. We will also present results from phot1 and phot2 mutants under various light conditions that are providing a better understanding of the role each photoreceptor plays in the response. Utilization of a GFP::mouse talin construct that highlights filamentous actin, time lapse movies, and other microscopic analyses that provide visual information about the mechanism of movement will be shown. Finally, data from alternative techniques used to analyze a possible requirement for red light will also be presented.
