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Investigating Tissue- and Organ-specific Phytochrome Responses using FACS-assisted Cell-type Specific Expression Profiling in Arabidopsis thaliana
Published on: May 29, 2010
Mutations affecting light regulation of nuclear genes encoding chloroplast glyceraldehyde-3-phosphate dehydrogenase
Chui Sien Chan1, Hsiao-Ping Peng, Ming-Che Shih
1Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242, USA.
Abstract:
Expression of nuclear genes that encode the A and B subunits of chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPA and GAPB) of Arabidopsis is known to be regulated by light. We used a negative selection approach to isolate mutants that were defective in light-regulated expression of the GAPA gene. Two dominant mutants belonging to the same complementation group, uga1-1 and uga1-2, were then characterized. These two mutants showed a dramatic reduction in GAPA mRNA level in both mature plants and seedlings. Surprisingly, mutations in uga1-1 and uga1-2 had no effect on the expression of GAPB and several other light-regulated genes. In addition, we found that the chloroplast glyceraldehyde-3-phosphate dehydrogenase enzyme activity of the mutants was only slightly lower than that of the wild type. Western-blot analysis showed that the GAPA protein level was nearly indistinguishable between the wild-type and the uga mutants. These results suggested that posttranscriptional control was involved in the up-regulation of the GAPA protein in the mutants. The uga1-1 mutation was mapped to the bottom arm of chromosome V of the Arabidopsis genome.
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