Journal Article

Investigations on the Photoregulation of Chloroplast Movement and Leaf Positioning in Arabidopsis

In-Seob Han, Hae-Young Cho, Akhi Moni, Ah-Young Lee and Winslow R. Briggs

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 54, issue 1, pages 48-56
Published in print January 2013 | ISSN: 0032-0781
Published online July 2012 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcs098

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We recently investigated the roles of the phototropin 1 (PHOT1) LOV (light, oxygen or voltage) domains in mediating phototropic curvature in transgenic Arabidopsis seedlings expressing either wild-type PHOT1 or PHOT1 with one or both LOV domains inactivated by a single amino acid replacement. We have now investigated the role of the PHOT1 LOV domains in chloroplast movement and in leaf positioning in response to blue light. Low fluence rate blue light is known to mediate a chloroplast accumulation response and high fluence rate blue light an avoidance response in Arabidopsis leaves. As was the case for phototropism, LOV2 of PHOT1 is essential for chloroplast accumulation and LOV1 is dispensable. PHOT1 LOV2 is also essential to maintain developing primary leaves in a horizontal position under white light from above and LOV1 is again dispensable. A red light pulse given to dark-adapted light-grown plants followed by 2 h of darkness enhances both the chloroplast accumulation response under dim blue light and the chloroplast avoidance response under strong blue light. The effect is far-red reversible. This photoreversible response is normal in a phyB null mutant but does not appear in a phyA null mutant. These results suggest that phyA mediates the enhancement, induced by a red light pulse, of blue light-induced chloroplast movements.

Keywords: Arabidopsis; Chloroplast; movement; LOV; domain; Phototropin; Phytochrome

Journal Article.  5283 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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