Abstract
Relative quantities of DNA in individual nuclei of stem and leaf epidermal cells of Arabidopsis were measured microspectrofluorometrically using epidermal peels. The relative ploidy level in each nucleus was assessed by comparison to root tip mitotic nuclei. A clear pattern of regular endopolyploidy is evident in epidermal cells. Guard cell nuclei contain levels of DNA comparable to dividing root cells, the 2C level (i.e., one unreplicated copy of the nuclear DNA). Leaf trichome nuclei had elevated ploidy levels of 4C, 8C, 16C, 32C, and 64C, and their cytology suggested that the polyploidy represents a form of polyteny. The nuclei of epidermal pavement cells were 2C, 4C, and 8C in stem epidermis, and 2C, 4C, 8C, and 16C in leaf epidermis. Morphometry of epidermal pavement cells revealed a direct proportionality between nuclear DNA level and cell size. A consideration of the development process suggests that the cells of highest ploidy level are developmentally oldest; consequently, the developmental pattern of epidermal tissues can be read from the ploidy pattern of the cells. This observation is relevant to theories of stomate spacing and offers opportunities for genetic analysis of the endopolyploidy/polyteny phenomenon.
Full Text
The Full Text of this article is available as a PDF (1.5 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Coleman A. W., Maguire M. J., Coleman J. R. Mithramycin- and 4'-6-diamidino-2-phenylindole (DAPI)-DNA staining for fluorescence microspectrophotometric measurement of DNA in nuclei, plastids, and virus particles. J Histochem Cytochem. 1981 Aug;29(8):959–968. doi: 10.1177/29.8.6168681. [DOI] [PubMed] [Google Scholar]
- Croxdale J., Smith J., Yandell B., Johnson J. B. Stomatal patterning in Tradescantia: an evaluation of the cell lineage theory. Dev Biol. 1992 Jan;149(1):158–167. doi: 10.1016/0012-1606(92)90272-i. [DOI] [PubMed] [Google Scholar]
- De Rocher E. J., Harkins K. R., Galbraith D. W., Bohnert H. J. Developmentally regulated systemic endopolyploid in succulents with small genomes. Science. 1990 Oct 5;250(4977):99–101. doi: 10.1126/science.250.4977.99. [DOI] [PubMed] [Google Scholar]
- Galbraith D. W., Harkins K. R., Knapp S. Systemic Endopolyploidy in Arabidopsis thaliana. Plant Physiol. 1991 Jul;96(3):985–989. doi: 10.1104/pp.96.3.985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kausch A. P., Horner H. T. Increased nuclear DNA content in raphide crystal idioblasts during development in Vanilla planifolia L. (Orchidaceae). Eur J Cell Biol. 1984 Jan;33(1):7–12. [PubMed] [Google Scholar]