Mutations Affecting Light Regulation of Nuclear Genes Encoding Chloroplast Glyceraldehyde-3-Phosphate Dehydrogenase in Arabidopsis

• Published in: Plant physiology (Bethesda) Vol. 130; no. 3; pp. 1476 - 1486
• Main Authors: Chui Sien Chan, Hsiao-Ping Peng, Shih, Ming-Che
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.11.2002
• Subjects: Arabidopsis - genetics; Arabidopsis - radiation effects; Cell Nucleus - genetics; Chloroplasts; Chloroplasts - enzymology; Chromosome Mapping; Dehydrogenases; Gene expression regulation; Gene Expression Regulation, Enzymologic - genetics; Gene Expression Regulation, Enzymologic - radiation effects; Gene Expression Regulation, Plant - genetics; Gene Expression Regulation, Plant - radiation effects; Genes; Genetic mutation; Genetics, Genomics, and Molecular Evolution; Glyceraldehyde-3-Phosphate Dehydrogenases - genetics; Light; Messenger RNA; Mutation - genetics; Plant cells; Plants; RNA; Seedlings
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.007849

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.