Diurnal Changes in Tissue Leaf Levels of Tryptophan, Tyrosine and Amine Metabolites in Sedum morganianum and Sedum pachyphyllum

Diurnal changes in tissue leaf levels of tryptophan, tyrosine, norepinephrine, serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) were investigated in Sedum morganianum (Burros tail) and Sedum pachyphyllum (Jellybean). We found that tissue 5-HIAA levels are decreased during the light period while 5-HT and norepinephrine levels are increased during the light period in both species. On the other hand, in Sedum morganianum both tissue tryptophan and tyrosine levels were decreased during the light period while in Sedum pachyphyllum both tissue tryptophan and tyrosine levels are increased during the light period. These results indicate that tryptophan, tyrosine and several related metabolites undergo diurnal fluctuations and that significant species differences may occur.