Effect of cadmium ions on proteolytic activity in sunflower cotyledons

LB PENA; SM GALLEGO

Bariloche, Río Negro

Congreso; XXXIX Reunión Anual Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2003

SAIB

Proteolysis removes abnormal or damaged proteins from the cell, regulates protein processing and intracellular protein levels, working as a cellular housekeeper. By means of proteolysis, cell can control the short-lived regulatory proteins that affect processes such as signal transduction and reception, transcription, division and cellular growth. The aim of the present study was to elucidate the effect of cadmium ion (Cd) on protease activity in sunflower cotyledons. Plants were grown in vermiculite, and after 10 days they were transferred to hydroponic medium with cadmium in Hoagland´s nutrient solution during 4 days. Treatments with 100 and 200 µM Cd produced a 20% increase in cotyledon protease activity, respect to the controls. Protease isoforms were separated by gel electrophoresis (SDS-PAGE 10%, 0,5% gelatin). Two isoforms were modified by cadmium treatments as compared to controls. The highest molecular weight isoform (less mobility) showed lower activity in cadmium-treated cotyledons, while the lowest molecular weight isoform showed higher protease activity in cadmium-treated cotyledons. These results suggest a direct relationship between cadmium stress and protease activity in sunflower cotyledons. The types of proteases involved in cadmium-induced senescence will be studied in order to establish the role of these isoforms in sunflower cotyledons under cadmium stress and their relationship with the proteases involved in natural senescence.