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Cellular Pathways of Red-Light-Induced Phototropism in Arabidopsis roots

Molas, Maria Lia
http://rave.ohiolink.edu/etdc/view?acc_num=miami1185051870

Abstract Details

2007, Doctor of Philosophy, Miami University, Botany.
Plants direct their growth in response to unidirectional light, while aerial parts curve toward light (i.e. positive phototropism), roots typically grow away from light (i.e. negative phototropism). Our laboratory has discovered a positive response to red light in Arabidopsis roots that is mediated by phytochrome A and B (PHYA and PHYB). However, PHYA- and PHYB-down-stream events are largely unknown as well as the nature of the intermediate molecules involved in the process. The overall objective of this study was to identify the molecules involved in transducing the red light (RL) signal down-stream the photoreceptors. High-throughput microarray-based analyses were conducted to characterize the gene expression changes in roots of Arabidopsis seedlings exposed to unidirectional red light. Several factors acting downstream of phytochromes in red-light signaling in roots were identified. As a result of this investigation, we obtained a list of candidate genes potentially mediating red light phototropic response in roots. For example, PHYTOCHROME KINASE 1 (PKS1), LONG HYPOCOTYL 5 (HY5), EARLY FLOWERING 4 (ELF4), GIGANTEA (GI), SUPPRESSOR OF PHYTOCHROME A RESPONSES 1 (SPA1), CONSTITUTIVE PHOTOMORPHOGENIC 1-like (COP1-like) and members of the RPT2/NPH3 (ROOT PHOTOTROPIC 2/NON PHOTOTROPIC HYPOCOTYL 3) family, which have been shown to mediate blue-light-induced phototropism, were also differentially regulated in roots under red light. To determine which of these genes mediate red-light-based phototropism in roots, we studied the phenotypic response to unilateral red light of null mutants using a high-resolution computer-based feedback system. Examination of the pks1 null mutant demonstrated that PKS1 is part of the pathway downstream of PHYA that is involved in red-light-based root phototropism. Moreover, our study suggests that PKS1 activates a PHYA-dependent signaling cascade promoting a negative response to RL. As a working model, we propose that PHYA controls RL phototropism by two different pathways. One pathway is PKS1- independent, and a second pathway is PKS1-dependent, both of them having opposite effects relative to each other. Thus, PKS1 emerges as a common intermediary in both red and blue light phototropism, supporting the growing body of data that indicates an interaction between blue and red light signaling pathways.
John Kiss (Advisor)
119 p.
Biology, Botany
Phototropism; Roots; Red light

Recommended Citations

Citations

  • Molas, M. L. (2007). Cellular Pathways of Red-Light-Induced Phototropism in Arabidopsis roots [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1185051870

    APA Style (7th edition)

  • Molas, Maria. Cellular Pathways of Red-Light-Induced Phototropism in Arabidopsis roots. 2007. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1185051870.

    MLA Style (8th edition)

  • Molas, Maria. "Cellular Pathways of Red-Light-Induced Phototropism in Arabidopsis roots." Doctoral dissertation, Miami University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1185051870

    Chicago Manual of Style (17th edition)

miami1185051870
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© 2007, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.