Diurnal fluctuations of the alkaloid concentration in latex of poppy Papaver somniferum is due to day–night fluctuations of the latex water content

Abstract

In this paper we show the diurnal variation in latex water content in the laticifer system of the opium poppy and relate this variation to the observed variation in alkaloid concentration in the latex. A pronounced, opposed variation to the diurnal water fluctuations are shown for the major opium alkaloids, morphine, codeine and noscapine in the poppy cultivar Parmo under dry weather conditions in Denmark in 1994. Diurnal fluctuations of the alkaloid concentration in the opium poppy latex have previously been explained as a result of rapid metabolism in the biosynthetic sequence leading to morphine. Our results, however, disagree with this explanation as a significant correlation between the diurnal fluctuation in the latex water content and that of the alkaloids morphine, codeine and noscapine can be demonstrated. It is concluded that the observed diurnal fluctuations in the concentration of the major alkaloids are not reflections of enzymatic processes but the result of water transport between the laticifers and the surrounding vascular tissue.