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Gene Profiling of Arabidopsis Shoots and Roots in Response to Red Light.    A.L. Kuntz, M.L. Molas, and J.Z. Kiss. Dept. of Botany, Miami Univ., Oxford, OH.

   Red light influences the growth and development of shoots which are primarily responsible for photosynthesis.  In addition, different processes in roots, such as gravitropism, phototropism, and lateral root and root hair formation are affected by exposure to such a light stimulus.  Plant organs sense red/far red light through the phytochromes, a family of diverse signal-transducing protein photoreceptors.  Phytochromes can perceive, interpret, and transduce red light signals in order to modulate early photoresponsive genes.  Most studies to date have been with whole seedlings; however, recent experiments have shown that light exposure results in distinct expression changes in the genome in different organs (cotyledon, hypocotyl, and root) of Arabidopsis seedlings.  As a follow-up to these reports, we performed experiments with Arabidopsis seedlings that were grown for 7 days in either complete darkness or in darkness followed by exposure to 1 hour of continuous red light from above.  Studies are in progress using microarray analysis to examine and compare the gene expression profiles of shoots and roots of Arabidopsis grown in these two different light regimes.  The long-term goal is to determine how plants integrate inputs from multiple light and gravity perception systems, and these experiments are related to our upcoming project using the European Modular Cultivation System (EMCS) on the ISS.

(Supported by the Ohio Plant Biotechnology Consortium and the Miami U. Undergraduate Summer Scholars Program.)