The data mentioned above indicate that the melatonin rhythm in C. rubrum is similar to the rhythms described in vertebrates. Therefore, we investigated possible effects of melatonin application on photoperiodic flower induction of C. rubrum. 4.5-day-old plants were induced to flowering by a single 12-h darkness and the chemicals, dissolved in DMSO and diluted with water, were applied onto the cotyledons and apical parts at different times. The percentage of flowering plants was assessed after 7 days of futher growth in constant light.
Melatonin, several putative precursors, melatonin agonists and antagonists and inhibitors of tryptophan decarboxylase were tested. Of these compounds, only melatonin and the agonist CGP 52608 showed significant effects. CGP 52608 (a thiazoli-dine dione) was shown to bind specifically to putative human nuclear melatonin receptors RZRa (13). CGP 52608 in concentrations from 2 x 10-5M to 3 x 10-4M reduced flowering when applied 3 or 1 h before, or 2 h after the beginning of 12-h darkness. The effect was dose-dependent. Another experiment showed that 2 x 10-4M CGP 52608 decreased flowering if applied in the interval from 3 h before to 6 h after the beginning of darkness. Later application was ineffective. The treatment with 2 x 10-5M to 5 x 10-4M melatonin 1 h before the beginning of darkness also reduced flowering. The application of both melatonin and CGP 52608 together was even more efficient. No signs of toxicity were observed even with the highest concentrations employed.
Our results support the notion that melatonin might actually have similar functions in plants as it has in animals. The aim of our future research is either to confirm, or reject this hypothesis.
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A Guide to Natural Sleep Remedies. Many of us experience the occasional night of sleeplessness without any consequences. It is when the occasional night here and there becomes a pattern of several nights in arow that you are faced with a sleeping problem. Repeated loss of sleep affects all areas of your life The physical, the mental, and theemotional. Sleep deprivation can affect your overall daily performance and may even havean effecton your personality.