Effects of light intensity on carbon-nitrogen metabolism and secondary metabolite of Catharanthus roseus leaves

The influence of different light intensities(100%, 42.5% and 12.5%)on carbon-nitrogen metabolism of Catharanthus roseus leaves was studied by measured the contents of C-N compounds and the activities of related enzymes. With the decrease of light intensity, the contents of starch and soluble sugar dropped while the contents of soluble protein, free amino acid and nitrate increased. The difference of enzymes activities involved in carbon and nitrogen metabolism under different light intensity were significant (P0.05). With the decrease of light intensity, the activities of amylase, sucrose phosphate synthase (SPS), nitrate reductase (NR) and glutamine synthase (GS) decreased while the activity of sucrose synthase (SS) increased.With the decrease of light intensity, total flavonoid contents decreased, contents and yield of vinblastine and vincristine showed a tendency of increase after decrease while contents and yield of vindoline and atharanthine always increased.