| Abstract Detail
Tropisms Molas, Maria L [1], Palmieri, Maria [2], Kiss, John [3]. PKS1 and PHYA are involved in red-light-based positive phototropism in roots. Phototropism is the directed growth of an organ in response to unidirectional light. While aerial parts of the plant curve toward a source of light (i.e. positive phototropism), roots growth typically away from the source of light (i.e. negative phototropism). However, we have recently discovered a novel phototropic response in Arabidopsis roots (i.e. positive phototropism in response to red light). This photoresponse is mediated by phytochrome A and B (PHYA and PHYB). Upon light stimulation, PHYA and PHYB phososphorylate a photochrome kinase substrate 1 (PKS1) in the cytoplasm. The active forms of PHYA and PHYB that did not interact with PKS1 migrate to the nucleus and activate light-regulated genes. In this study, we investigated the participation of PHYA and PKS1 in the positive phototropic response to red light in roots. In roots, PKS1 expression is predominantly controlled by PHYA with a possible role of PHYB as well. Using a high-resolution feedback system, we measured the angle of curvature of root tips of phyA, pks1 and phyA pks1 mutants after exposure to unidirectional light. We found that PHYA is essential for a positive response to red light and that PKS1 attenuates PHYA action. As a working model, we propose that in roots, PHYA counteracts a negative response to white light, which predominates over the red light positive response. In addition, PKS1 seems to mitigate PHYA action since abolition of both PKS1and PHYA produce a negative curvature in phyapks1mutant that is significantly less than phyA mutant. Studies involving PHYB and PKS1 are in progress to elucidate how these molecules modulate positive phototropism in roots.
Final support was provides by NASA grant NCC2-1200.
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1 - Miami University, Botany, Pearson Hall, Oxford, Ohio, 45056, Argentina
2 - University of Cincinnati, Office of Institutional Research
3 - Miami University, Botany
Keywords:
phototropism
PKS1
red light.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P32005
Abstract ID:1041 |
