Biochemical responses in sunflower and wheat under cadmium stress

M.D. GROPPA; M.P. BENAVIDES; M.L. TOMARO

Córdoba, Argentina

Congreso; XXXVII Reunión Anual de SAIB.; 2001

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

The toxic effects of heavy metals on crop plants is receiving considerable attention in the last years. The objective of this work was the study the effect on germination of three concentrations of cadmium (0.1, 0.5 and 1 mM), and proline, polyamines and ethylene levels in sunflower cotyledons and wheat leaves of eight–days plants. Cadmium enhanced germination in both species. However, in eight-days plants, a decrease in FW/DW was observed in plants treated with 0.5 and 1 mM Cd. Ethylene production showed a similar pattern in sunflower and wheat, with an important decline of 77% and 60% at 1 mM Cd, respectively. In sunflower cotyledons, putrescine increased about 10 fold and proline concentration increased 40%, 600% and 800 % with 0.1, 0.5 and 1 mM Cd respectively. Elevated cadmium concentrations caused a clear alteration in nitrogen metabolism, evidenced by the variation in proline and polyamines. Proline is well known to increase under osmotic stress. The enhancement in proline content in sunflower cotyledons was probably due to an osmotic alteration produced by cadmium. Ethylene decreased while putrescine increased at 1 mM Cd, another evidence that polyamines and ethylene could vary in opposite ways under several stress situations. As polyamines and proline are proposed as antioxidants, their enhancement might also be part of the protective response against the oxidative damage generated by cadmium.