Effect of Light on Alkaloid Accumulation in Cell Cultures of Nicotiana Species

Abstract

The effect of light on alkaloid accumulation in a range of cell cultures of tobacco was determined. Cell suspension cultures of Nicoriana rabacwn L. cv. Wisconsin-38 with differing degrees of photosynthetic activity, callus cultures of N. glauca Graham, root cultures of N. rustica L. and shoot cultures of N. tabacum were used. The alkaloid content of green illuminated cultures was greatly reduced compared with non-green cultures grown in the dark, but decreased accumulation did not correlate with increasing photosynthetic activity. The accumulation of all of the major alkaloids was affected, regardless of the species of tobacco used. Transfer of N. glauca callus from the dark into the light caused a decrease in alkaloid accumulation, while moving cultures from the light into the dark resulted in an increase in alkaloid content. In root cultures light caused a reduction in growth, which affected alkaloid synthesis. In shoot cultures there were only traces of alkaloid detectable, regardless of whether or not cultures were illuminated. Light appeared to cause a non-photosynthetic suppression of alkaloid accumulation in visibly undifferentiated cultures, and this effect was modified in visibly differentiated cultures.