Poster: Cytoskeleton: Structure & Function
Abs #
1110: Microtubules and microfilaments control the movement and morphology of non-green plastids and stromules
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Presenter: |
Kwok, Ernest Y., eyk5@cornell.edu |
Authors | Kwok, Ernest Y. (A) Hanson, Maureen R. (A) | | Affiliations: |
(A): Department of Molecular Biology and Genetics, Cornell University
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Studies of plastid structure and dynamics have been limited primarily to chloroplasts because of their ease of observation. The recent application of plastid-targeted green fluorescent proteins (GFP) has allowed the observation of non-green plastids in vivo. Investigations of plastid-targeted GFP in a variety of higher plants has led to renewed interest in stroma-filled tubules, or stromules, that project from the plastid envelope membrane. These structures are observed at highest frequency in non-green tissues such as roots, cultured cells, and etiolated hypocotyls. Stromules can be many times longer than the length of the plastid body and are extremely dynamic, moving within the cell and joining adjacent plastids. We have used the actin inhibitor cytochalasin D and the tubulin inhibitor amiprophosmethyl to investigate the control of morphology and movement of stromules and non-green plastids in etiolated hypocotyls. Our results suggest that both microfilament and microtubule cytoskeletal systems contribute to the shape and motility of non-green plastids and their stromules. Actin and tubulin appear to act independently in specifying plastid and stromule structure. Movement of non-green plastids and stromules is mostly promoted by microfilaments. However, microtubules have an inhibitory effect on non-green plastid movement. These results are striking because chloroplast movement in angiosperms has previously been understood to be controlled by actin alone and there is little evidence for interaction between microtubules and chloroplasts. In addition, photobleaching studies of plastids joined by stromules indicate that cytoskeleton inhibitors do not have a major effect on GFP movement through stromules.
