Abstract
Quantities of DNA were estimated in the nuclei of mechanically isolated egg and zygote protoplasts in two cultivars of barley using 4[prime],6-diamidino-2-phenylindole staining and microfluorometry. Unlike many previous studies on DNA amounts within the sex cells of flowering plants, we obtained consistent and unambiguous results indicating that the egg and sperm nuclei are at the 1C DNA level (basic haploid amount) at the time of karyogamy. Karyogamy was initiated within 60 min postpollination, and the male chromatin became completely integrated into the egg nucleus within 6 to 7 hr postpollination (hpp). Zygotic nuclear DNA levels began to increase at ~9 to 12 hpp in cultivar Alexis and at 12 to 15 hpp in cultivar Igri. The 4C DNA complement was reached in most zygotes by 22 to 26 hpp in cultivar Alexis and by 23 to 29 hpp in cultivar Igri. These data are fundamental to a better understanding of fertilization and zygote maturation in flowering plants. They are also relevant to studies in which the timing of zygotic DNA replication is of interest, such as ongoing investigations on genetic transformations in barley using the microinjection technique.
Full Text
The Full Text of this article is available as a PDF (798.6 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Coleman A. W., Goff L. J. Applications of fluorochromes to pollen biology. I. Mithramycin and 4',6-diamidino-2-phenylindole (DAPI) as vital stains and for quantitation of nuclear DNA. Stain Technol. 1985 May;60(3):145–154. doi: 10.3109/10520298509113905. [DOI] [PubMed] [Google Scholar]
- PATAU K. Absorption microphotometry of irregular-shaped objects. Chromosoma. 1952;5(4):341–362. doi: 10.1007/BF01271492. [DOI] [PubMed] [Google Scholar]
- SWIFT H. The constancy of desoxyribose nucleic acid in plant nuclei. Proc Natl Acad Sci U S A. 1950 Nov;36(11):643–654. doi: 10.1073/pnas.36.11.643. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WOODARD J. W. DNA in gametogenesis and embryogeny in Tradescantia. J Biophys Biochem Cytol. 1956 Nov 25;2(6):765–776. doi: 10.1083/jcb.2.6.765. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Woodcock C. L., Bell P. R. The distribution of deoxyribonucleic acid in the female gametophyte of Myosurus minimus. Histochemie. 1968;12(4):289–301. doi: 10.1007/BF00278301. [DOI] [PubMed] [Google Scholar]