Abstract Detail
Photomorphogenesis Han, Insoeb [1], Briggs, Winslow R. [2]. The role of the phototropin 1 LOV domains in the regulation of chloroplast movement and leaf position and of phytochrome regulation of chloroplast movement in Arabidopsis thaliana seedlings. We recently investigated the roles of the phototropin 1 (phot1) LOV domains in mediating phototropic curvature in transgenic Arabidopsis seedlings expressing either wild-type phot1 or phot1 with one or both LOV domains inactivated (Cho et al., Plant Physiol. 143: 517, (2007). We have now investigated the role of the phot1 LOV domains in chloroplast movement and in leaf orientation to light. Low fluence-rate blue light is known to mediate a chloroplast accumulation response and high fluence-rate light an avoidance response in Arabidopsis leaves. As was the case for phototropism, LOV2 is essential for chloroplast accumulation and LOV1 is dispensable. Transgenic plants expressing phot1 with only LOV2 functional show greater chloroplast accumulation at higher fluence rates of blue light than those expressing phot1 with both LOV1 and LOV2 functional, suggesting that the role of LOV1 may be to down-regulate the LOV2-mediated response. 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 seedlings followed by two hours of darkness strongly enhances chloroplast accumulation under dim blue light. The effect is completely far-red reversible. We are currently investigating phytochrome mutants to determine which phytochrome is responsible.
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1 - University of Ulsan, Biology, Kyungnam, Ulsan, 680-749, Korea
2 - Carnegie Institution of Washington, Plant Biology
Keywords:
phototropin
Phytochrome
LOV domain
Chloroplast movement.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P31014
Abstract ID:1249 | 