Effects of aluminum on DNA synthesis, cellular polyamines, polyamine biosynthetic enzymes and inorganic ions in cell suspension cultures of a woody plant, Catharanthus roseus


Increased aluminum (Al) solubility in soil waters due to acid precipitation has aroused considerable interest in the problem of Al toxicity in plants. In the present study, an in vitro suspension culture system of Catharanthus roseus (L.) G. Don was used to analyze the effects of aluminum on several biochemical processes in these cells. The aliphatic polyamines, spermine and spermidine, and their precursor, putrescine, have been implicated in a number of stress responses of plants. Addition of 0.2, 0.5 or 1.0 mM AICl3 to cells cultured for 3 days caused a small but significant increase in cellular levels of putrescine at 4 h followed by a sharp decline by 16 h. There was no further decline in levels of putrescine during the next 32 h. Spermidine levels did not change appreciably compared to those in the control cultures. However, spermine levels increased by 2-3 fold at 24 and 48 h. Cellular activities of arginine decarboxylase (ADC; EC and S-adenosylmethionine decarboxylase (SAMDC: EC 4. 1.1.50) were both inhibited by 20-25% at 4 and 7 h. Ornithine decarboxylase (ODC: EC was less than 10% of ADC activity at all times. Whereas all concentrations of Al caused a slight decrease in total cell number, cell viability was affected only by 1.0 mM Al. There was a decrease in the cellular levels of Ca, Mg, Na, K, Mn, P and Fe in the cells treated with Al at 4 h, but a significant increase by 16 and 24 h. The results presented here suggest that both the absolute amounts of Al and the length of exposure to it are important for cell toxicity.

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Physiologia Plantarum


Wiley Blackwell

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