stress in callus of hippocratea excelsa: catalase activity, hydrogen peroxide content and canophyllol accumulation

Abstract

Stress factors often induce oxidative stress in plant cells, generally leading to the synthesis of signal molecules that activate a range of signal transduction pathways and antioxidants. One of the signal molecules produced under stress is H2O2, which has been associated to production in vitro of secondary metabolites (SM) and to antioxidant activity. Canophyllol production by Hippocratea excelsa was used as an example to show the enhanced production of SM under stress. Seeds obtained from fruits were cultured in vitro. Two stresses were applied: nutritional, by reducing the amount of N-2, and osmotic, using polyethylene glycol. Canophyllol, H2O2 content and catalase activity were measured. Nutritional stress caused a different response than osmotic stress for catalase activity and canophyllol accumulation, whereas H2O2 contents increased under both stresses. The highest amount of canophyllol (8 times the control) was obtained under the nutritional stress, in the treatment with 25% of control N-2 strength. This work demonstrates that the responses of canophyllol production and catalase activity in H. excelsa callus are differentially signaled by the different stress factors.