Abstract
We have investigated the accumulation of Cat2 and Cat3 catalase transcripts in 6-7-day postimbibition leaves of normally pigmented and pigment-deficient maize seedlings under different light regimes. In seedlings of normal inbred maize lines Cat2 mRNA accumulates to significantly higher levels in either continuous light or a diurnal light/dark cycle than in continuous dark. In contrast to the high levels of the Cat2 message observed in their wild-type siblings, carotenoid-deficient mutants accumulate Cat2 mRNA at barely detectable levels. Mutants deficient in chlorophylls, but having normal carotenoid levels, accumulate normal levels of Cat2 mRNA. This suggests that both light and carotenoids are required for the normal accumulation of the Cat2 message. The steady-state level of Cat3 RNA exhibits a dramatic diurnal variation when seedlings are grown under a 24-hr light/dark cycle. We have previously shown that this variation is at the level of Cat3 gene transcription and is under the control of a novel circadian rhythm. In this study we show that both pigment-deficient mutants and their wild-type siblings exhibit the normal diurnal pattern of Cat3 RNA accumulation. This indicates that photosynthetic pigments, allelic variation, and genetic background do not directly affect the temporal pattern of Cat3 accumulation in leaves. We observed, however, that when normal plants are grown in either continuous light or continuous dark, the Cat3 transcript in leaves is present at uniformly high levels throughout the 24-hr sampling period. Because the Cat3 gene is continually transcribed in leaves in the absence of a cyclic light regime, the normally observed diurnal variation of Cat3 gene expression is apparently the result of a circadian-regulated transcriptional repressor.
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Selected References
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- Giuliano G., Hoffman N. E., Ko K., Scolnik P. A., Cashmore A. R. A light-entrained circadian clock controls transcription of several plant genes. EMBO J. 1988 Dec 1;7(12):3635–3642. doi: 10.1002/j.1460-2075.1988.tb03244.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hall J. C., Rosbash M. Mutations and molecules influencing biological rhythms. Annu Rev Neurosci. 1988;11:373–393. doi: 10.1146/annurev.ne.11.030188.002105. [DOI] [PubMed] [Google Scholar]
- McClung C. R., Fox B. A., Dunlap J. C. The Neurospora clock gene frequency shares a sequence element with the Drosophila clock gene period. Nature. 1989 Jun 15;339(6225):558–562. doi: 10.1038/339558a0. [DOI] [PubMed] [Google Scholar]
- Redinbaugh M. G., Sabre M., Scandalios J. G. Expression of the maize Cat3 catalase gene is under the influence of a circadian rhythm. Proc Natl Acad Sci U S A. 1990 Sep;87(17):6853–6857. doi: 10.1073/pnas.87.17.6853. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Redinbaugh M. G., Sabre M., Scandalios J. G. The distribution of catalase activity, isozyme protein, and transcript in the tissues of the developing maize seedling. Plant Physiol. 1990 Feb;92(2):375–380. doi: 10.1104/pp.92.2.375. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Scandalios J. G. Subunit dissociation and recombination of catalase isozymes. Proc Natl Acad Sci U S A. 1965 May;53(5):1035–1040. doi: 10.1073/pnas.53.5.1035. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Smith S. M., Ellis R. J. Light-stimulated accumulation of transcripts of nuclear and chloroplast genes for ribulosebisphosphate carboxylase. J Mol Appl Genet. 1981;1(2):127–137. [PubMed] [Google Scholar]
- Stayton M. M., Brosio P., Dunsmuir P. Photosynthetic Genes of Petunia (Mitchell) Are Differentially Expressed during the Diurnal Cycle. Plant Physiol. 1989 Mar;89(3):776–782. doi: 10.1104/pp.89.3.776. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wadsworth G. J., Scandalios J. G. Molecular characterization of a catalase null allele at the Cat3 locus in maize. Genetics. 1990 Aug;125(4):867–872. doi: 10.1093/genetics/125.4.867. [DOI] [PMC free article] [PubMed] [Google Scholar]