Polyamine metabolism in sunflower and wheat leaf discs under cadmium or cupper stress

GROPPA MD; BENAVIDES MP; TOMARO ML

PLANT SCIENCE

Elsevier

Año: 2003 vol. 164 p. 293 - 299

0168-9452

The influence of Cd2+ or Cu2+ on polyamine (Pa) metabolism and ethylene evolution was studied in sunflower and wheat leaf-discs. Both metals increased putrescine (Put) content in wheat leaves 280 and 90%, respectively, but reduced this Pa in sunflower leaves by about 50% of the control values. Spermidine content was diminished in cadmium and copper sunflower treated leaves (41 and 79%, respectively) while spermine was reduced by both metals in wheat (around 40%). In sunflower leaves, both metals greatly reduced arginine decarboxylase (ADC) activity, while ornithine decarboxylase (ODC) was only decreased by cadmium. However, in wheat leaves, cadmium increased ADC and ODC activities (210 and 2200% over the control, respectively), and Cu2+ raised ODC activity fivefold respect to the control, with the resulting increase in Put concentration. Moreover, the decreased diamine oxidase activity observed with both metals in wheat leaves might contribute to the high Put level observed. Cadmium and copper increased ethylene production sixfold in wheat leaves, while in sunflower leaves, only copper produced a great increment in the hormone (300% over the control).