[quote=SimonV]
It was very timely as my caffiene treated laevigata will hopefully bloom in about a month and I’ve decided to test for doubling this way instead of by root-tip squash incase I got incomplete doubling[/quote]
Simon,
I’m surprised that you are trying caffeine to double the chromosome number. The reports I’ve read suggest that caffeine is useful for reducing chromosome number by forcing an extra cell division … except Peña, et al., who observed cell fusion.
Karl
Peña, et al. Bimeiosis induced by caffeine. Chromosoma 83(2): 241-248. (1981)
A 0.1% caffeine solution has been injected into plants of rye at various stages of spike development. Cytokinesis was inhibited in the germ line, and the resulting binucleate cells underwent bimeiosis. Nuclear fusions occurred during cell divisions of the germ line, giving rise to mononucleate tetraploid PMCs which showed 14 bivalents instead of the expected up to 7 quadrivalents. A decrease in chiasma frequency was also noted.
Schlegel R, Pardee AB. Caffeine-induced uncoupling of mitosis from the completion of DNA replication in mammalian cells. Science. 1986 Jun 6;232(4755):1264-6.
Caffeine was shown to induce mitotic events in mammalian cells before DNA replication (S phase) was completed. Synchronized BHK cells that were arrested in early S phase underwent premature chromosome condensation, nuclear envelope breakdown, morphological “rounding up,” and mitosis-specific phosphoprotein synthesis when they were exposed to caffeine. These mitotic responses occurred only after the cells had entered S phase and only while DNA synthesis was inhibited by more than 70 percent. Inhibitors of protein synthesis blocked these caffeine-induced events, while inhibitors of RNA synthesis had little effect. These results suggest that caffeine induces the translation or stabilizes the protein product (or products) of mitosis-related RNA that accumulates in S-phase cells when DNA replication is suppressed. The ability to chemically manipulate the onset of mitosis should be useful for studying the regulation of this event in mammalian cells.
Fundamental and Molecular Mechanisms of Mutagenesis, Vol. 452 (1) (2000) pp. 67-72
Inducing somatic meiosis-like reduction at high frequency by caffeine in root-tip cells of Vicia faba
Yihua Chen, Lihua Zhang, Yihua Zhou, Yuxuan Geng and Zhenghua Chen
Abstract: Germinated seeds of Vicia faba were treated in caffeine solutions of different concentration for different durations to establish the inducing system of somatic meiosis-like reduction. The highest frequency of somatic meiosis-like reduction could reach up to 54.0% by treating the root tips in 70 mmol/l caffeine solution for 2 h and restoring for 24 h. Two types of somatic meiosis-like reduction were observed. One was reductional grouping, in which the chromosomes in a cell usually separated into two groups, and the role of spindle fibers did not show. The other type was somatic meiosis, which was analogous to meiosis presenting in gametogenesis, and chromosome paring and chiasmata were visualized.
So, would you recommend using pollen diametre as an indicator of ploidy in my caffienated laevigata? I have the control plant and the treated plant. If I can get pollen from both and compare them might that give some indication of doubling?