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

In this paper we show the diurnal variation in latex water content in the l aticifer system of the opium poppy and relate this variation to the observe d variation in alkaloid concentration in the latex. A pronounced, opposed v ariation to the diurnal water fluctuations are shown for the major opium al kaloids, morphine, codeine and noscapine in the poppy cultivar Parmo under dry weather conditions in Denmark in 1994. Diurnal fluctuations of the alka loid concentration in the: opium poppy latex have previously been explained as a result of rapid metabolism in the biosynthetic sequence leading to mo rphine. Our results, however. disagree with this explanation as a significa nt correlation between the diurnal fluctuation in the latex water content a nd that of the alkaloids morphine, codeine and noscapine can be demonstrate d. It is concluded that the observed diurnal fluctuations in the concentrat ion of the major alkaloids are not reflections of enzymatic processes but t he result of water transport between the laticifers and the surrounding vas cular tissue. (C) 1999 Elsevier Science Ltd. All rights reserved.