Control of Hypocotyl Elongation by Blue Light in Arabidopsis Seedlings

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A detailed description of the mechanisms plants use to sense and respond to their light environment is necessary for a complete understanding of plant development, which is important to those concerned with the practical uses of plants in agriculture and biotechnology. The activities funded by this award will provide molecular-level details about how the blue region of the light spectrum exerts its profound effects on Arabidopsis seedling growth and development. The mutants to be employed have lesions in genes that are believed to encode light receptors, such as the cryptochromes (CRY1 and CRY2) and photokinase (NPH1). By measuring the growth responses to blue light of the mutant seedlings with high resolution, and comparing them to the wild type, details will be learned about how the photoreception mechanism operates. Plants containing mutations in more than one photoreceptor will also be created and studied. This comparative kinetic analysis of the growth responses to blue light will indicate when a particular photoreceptor begins to exert its effect. Such information on timing will enable a very focused genomics-based search for genes that are turned on or off by biochemical pathways emanating from the various genetically-identified blue light receptors to cause the growth responses. This aspect of the project will employ microarrays of DNA on chips that represent the Arabidopsis genome. Once such blue-light regulated genes are identified, studies of their properties and functions will be initiated so that the signaling pathway becomes known at the molecular level. It is expected that the molecular details of light-signaling pathways will be an important component of the knowledge base that will support plant technologies of the future. The research supported by this award will also impact education through the involvement of postdoctoral, graduate, and undergraduate students.