Effects of several abiotic and biotic factors and plant hormones on growth, morophology, and camptothecin accumulation in Camptotheca acuminata seedlings

Abstract

This dissertation seeks to explore the effects of abiotic factors [nitrogen (N), sodium chloride (NaCl), and ultraviolet (UV) light], biotic factor [acetylsalicylic acid (ASA)], and plant hormones [benzyl adenine (BA) and naphthalene acetic acid (NAA)] on growth, morphology, and secondary metabolite, camptothecin (CPT, an anti-cancer compound) accumulation in Camptotheca acuminata. Five experiments were conducted with C. acuminata seedlings in a hydroponic system with commercial media and fluorescent lights and at 22-26 °C to investigate the effects of these five factors on height, weight, leaf number, leaf length, root to shoot ratio (RSR), specific leaf weight (SLW), CPT concentrations in leaves and/or roots, and final CPT yield in leaves which were collected in nondestructive harvestings. N deficiency decreased height, weight, leaf number, leaf length, and leaf chlorophyll concentration in comparison with N supplementation, but increased RSR, SLW, and CPT concentrations in leaves and roots. However, the CPT yield did not increase. NaCl addition reduced height, weight, leaf number, and leaf length, but increased SLW and CPT concentrations in leaves and roots. However, the CPT yield decreased. UV light short-term exposure had no effect on height, weight, leaf number, leaf length, RSR, and SLW, but increased leaf CPT concentration and yield after three weeks. ASA addition reduced plant height, weight, and leaf length, but increased SLW and leaf CPT concentration, and decreased CPT yield. BA application decreased height, but increased RSR and leaf CPT concentration, and had no effect on CPT yield. NAA application decreased height, weight, leaf number, leaf length, SLW, and CPT yield, but increased RSR, and had no effect on leaf CPT concentration. In conclusion, abiotic and biotic stresses reduced the growth and affected the morphology of C. acuminata seedlings in a hydroponic system. Abiotic stresses and biotic stress increased CPT concentration, but did not increase CPT yield (expect UV). Cytokinin up-regulated CPT concentration but had no effect on CPT yield, whereas auxin did not regulate CPT concentration but decreased CPT yield. A negative relationship between plant growth and CPT concentration existed under the treatments with N, NaCl, or ASA.