POLYAMINE METABOLISM IN SUNFLOWER PLANTS UNDER Cd or Cu STRESS

M.D. GROPPA; N.V. LASPINA; M.L. TOMARO; M.P. BENAVIDES

Viena, Austria

Congreso; 9th International Congress on Amino Acids and Proteins.; 2005

During the last years, it has been observed a significant increase of metal soil contamination. The aim of this work was to study polyamine metabolism under Cd or Cu stress in sunflower plants exposed to 0.1 and 1mM of the metals during 16 days. Growth was evaluated measuring the length of roots and shoots and the relative water content (RWC). Both metals produced an inhibition of the shoot growth only at 1 mM. Root growth was reduced by 0.1 and 1 mM Cd or 1 mM Cu. RWC was affected by both metals only at 1 mM from the 7 day of culture (to 60% and 45% of the controls). In shoots, Cd and Cu increased Put content 260% and 160% over the controls, respectively. In roots, both metals inceased Put content from day 7. Spermidine was only increased by 1 mM Cd in both shoots and roots. Spermine content raised in shoots by day 10 under Cd 1 mM and at day 16 with 1 mM Cu. In roots, spermine increased 200% with 1 mM Cd. Regarding biosynthetic enzymes, 1 mM Cu increased ADC activity from day 7, both in shoots and roots, without affecting ODC activity. Cadmium did not modify ADC activity, but increased ODC activity from the third day of treatment. DAO activity was modified differently depending on the day of treatment and/or tissue. The results obtained indicated that polyamine metabolism is modified under Cd or Cu stress, leading to the activation of ADC or ODC biosynthetic routes depending on the metal and tissue.