Plant Physiol, November 2002, Vol. 130, pp. 1476-1486
Mutations Affecting Light Regulation of Nuclear Genes Encoding
Chloroplast Glyceraldehyde-3-Phosphate Dehydrogenase in
Arabidopsis1
Chui Sien
Chan,
Hsiao-Ping
Peng, and
Ming-Che
Shih*
Department of Biological Sciences, University of Iowa, Iowa City,
Iowa 52242
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.
1
This work was supported by the U.S. Department
of Agriculture National Research Initiative Competitive Grants
Program (grant no. 9600717 to M.-C.S.).
*
Corresponding author; e-mail mcshih{at}blue.weeg.uiowa.edu; fax
319-335-3620.
© 2002 American Society of Plant Biologists
