Light-signaling pathways controlling seedling development in Ara

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  • Writer 이태화
  • 2014-01-17



Light-signaling pathways controlling seedling development in Arabidopsis


- Date/Time : Tue March 25., 2003


- Speaker :  Dr. Edgar Spalding

             - Dept. of Botany

             - University of Wisconsin at Madison

- Place : Life Science Bldg. #104

- For inquires : Professor Youngsook Lee Dept. of Life Science

               생명과학과 이영숙 교수 (☎279-2296)


- Abstract

     Photoreceptors that absorb specific regions of the light spectrum profoundly influence the development of seedlings. Blue light acting through the cryptochrome 1 (cry1) and phototropin 1 (phot1)photoreceptors influences the rate and direction of hypocotyl elongation during the establishment of Arabidopsis seedlings in order to position the photosynthetic apparatus most advantageously for future growth and development of the plant. Our efforts to understand the earliest phases of the signal transduction pathway initiated by these photoreceptors have focused on ion fluxes across the plasma membrane. Activation of calcium channels at the plasma membrane by phot1 is required for the initial phase of hypocotyl inhibition and activation of anion channels by cry1, also within seconds of blue light, is an early event in a growth-inhibition pathway that replaces the phot1 phase 30 min after the onset of irradiation. DNA microarrays were used to identify cry1-dependent genes that function downstream of the early ionic events in the control of hypocotyl growth in blue light. The genomic results indicated that gibberellin synthesis and auxin responses were suppressed by cry1 to inhibit growth, and this was supported by physiological studies. A molecular screen designed to identify the cry1-activated anion channel isolated a multidrug-resistance transporter of the ABC superfamily (MDR1). Mutation of the MDR1 transporter impaired polar auxin transport and, surprisingly, also enhanced gravitropism and phot1-mediated phototropism. These observations could all be explained by the finding that mutations in MDR1 prevented the proper basal localization of the PIN1 auxin efflux carrier in hypocotyl cells. Thus, genetic, genomic, and electrophysiological approaches can be combined to learn more details about how light affects seedling growth and d