Effect of NaCl on growth, morphology, and camptothecin accumulation in Camptotheca acuminata seedlings

Abstract

NaCl salt is shown to increase alkaloid accumulation in some plant species, but creates an extensive problem in plant cultivation. The effect of NaCl on Camptotheca acuminata Decaisne growth, morphology, and camptothecin accumulation (concentration and yield) was studied in a hydroponic culture system. High NaCl levels (above 75 mM) in growth media significantly reduced plant height, weight, leaf number, and leaf length but increased leaf weight. In contrast, low NaCl levels (below 75 mM) only moderately reduced growth and affected morphology. Our results suggest a concentration of 75 mM is the threshold for NaCl to exert a detrimental effect on C. acuminata seedlings. Furthermore, high NaCl levels (above 75 mM) increased camptothecin concentrations both in leaves and roots, whereas low NaCl levels (below 75 mM) had no effect on camptothecin concentrations. However, total leaf camptothecin yield, the product of leaf camptothecin concentration and total leaf dry weight per seedling, decreased with increasing NaCl concentration. There was a negative relationship between plant growth and camptothecin concentration. Our results suggest that high NaCl salinity increases camptothecin concentration, but is not helpful to achieve a high camptothecin yield. Therefore, a salty growth environment should be avoided for camptothecin production. Key words: Alkaloid, anti-cancer plant, HPLC, plant secondary metabolism