Two dominant photomorphogenic mutations of Arabidopsis thaliana identified as suppressor mutations of hy2 |
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Authors: | Byung Chul Kim Moon Soo Soh Bong Joong Kang Masaki Furuya Hong Gil Nam |
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Institution: | Department of Life Science, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, South Korea;Advanced Research Laboratory, Hitachi Ltd, Hatoyama, Saitama 350-03, Japan;Plant Molecular Biology and Biotechnology Research Center, Jinju, Kyungnam, 660-701, South Korea |
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Abstract: | By screening suppressor mutants of the hy2 mutation of Arabidopsis thaliana , two dominant photomorphogenic mutants, shy1-1D and shy2-1D , for two genetic loci designated as SHY1 and SHY2 ( s uppressor of hy 2 mutation) have been isolated. Both of these non-allelic, extragenic suppressor mutations of hy2 are located on chromosome 1 of the Arabidopsis genome. Both mutations suppress the elongated hypocotyl phenotype of hy2 by light-independent inhibition of hypocotyl growth as well as by increasing the effectiveness of light inhibition of hypocotyl elongation. The shy1-1D mutation is partially photomorphogenic in darkness with apical hook opening and reduced hypocotyl elongation. The shy2-1D mutant displays highly photomorphogenic characteristics in darkness such as true leaf development, cotyledon expansion, and extremely reduced hypocotyl growth. In regard to hypocotyl elongation, however, the shy2-1D mutation is still light sensitive. Examination of red/far-red light responses shows that the shy1-1D mutation suppresses the hypocotyl elongation of the hy2 mutation effectively in red light but not effectively in far-red light. The shy2-1D suppresses hypocotyl elongation of the hy2 mutation effectively in both red and far-red light. Both mutations can also suppress the early-flowering phenotype of hy2 and have a distinct pleiotropic effect on leaf development such as upward leaf rolling. The data obtained suggest that SHY1 and SHY2 represent a novel class of components involved in the photomorphogenic pathways of Arabidopsis . This is the first report on the identification of dominant mutations in the light signal transduction pathway of plants. |
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