ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of nitrogen forms on the camptothecin (CPT) content, tryptophan synthase (TSB) and tryptophan decarboxylase (TDC) activities in Camptotheca acuminata seedlings.</p><p><b>METHOD</b>The seedlings of C. acuminata with 6 pairs of leaves were subjected to 5 different NH4(+) -N/NO3(-) -N ratio (0 : 100, 75 : 25, 50 : 50, 25 : 75, 100 : 0) treatments by sand culture in a greenhouse. The CPT content, TSB activity in the young leaves and TDC in the stem barks of the seedlings were determined by HPLC on the 15th, 30th, 45th, 60th and 75th day, respectively.</p><p><b>RESULT</b>The obvious relationship between CPT content and nitrogen forms was observed. When NH4(+) - N /NO3(-) -N ratio was 25 : 75, CPT accumulation in young leaves displayed the best advantages (the highest value is 5.69 per thousand) and increased in the early 30 days of treatment and then declined. There was no obvious relationship between TSB activity in the young leaves and nitrogen forms. TDC activity in the stem bark was the highest when NH4(+) -N /NO3(-) -N ratio was 25 : 75, and the change of TDC activity paralleled to CPT content in the young leaves.</p><p><b>CONCLUSION</b>A short-term treatment that NH4(+) -N /NO3(-) -N ratio was 25:75 may gain high CPT content in the young leaves through enhancing the TDC activity in the stem bark of C. acuminata seedlings.</p>
Subject(s)
Aromatic-L-Amino-Acid Decarboxylases , Metabolism , Camptotheca , Metabolism , Camptothecin , Metabolism , Drugs, Chinese Herbal , Metabolism , Nitrogen , Chemistry , Pharmacology , Plant Leaves , Metabolism , Seedlings , Metabolism , Tryptophan Synthase , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of nitrogen concentration on the camptothecin (CPT) content in Camptotheca acuminata seedlings:</p><p><b>METHOD</b>The seedlings of C. acuminata with 6 pair of leaves were subjected to five nitrogen concentrations treatments by sand culture in a greenhouse. The CPT content in the seedlings was determined by HPLC on the 20th, 35th, 50th, 65th and 80th day respectively.</p><p><b>RESULT</b>The CPT content in the young leaves of C. acuminata seedlings supplied with different nitrogen concentration was significantly higher than that in other organs (P < 0.01), and it showed a single peak curve with the time course, the highest CPT content was observed on the 50th day after treatment. The CPT content in the young leaves obviously declined with increasing nitrogen concentration, and it reached the highest (6.72%) when nitrogen concentration was 4 mmol x L(-1), equal to 1.1 times that of 16 mmol x L(-1) nitrogen.</p><p><b>CONCLUSION</b>The results demonstrate that proper deficient nitrogen stress can significantly enhance CPT accumulation in young leaves of C. acuminata seedlings.</p>