[Zinc phytotoxicity and induction of stress proteins in bean (Phaseolus vulgaris L.)].

Bean seedlings (Phaseolus vulgaris L., cv. fin de Bagnol) were grown for ten days in nutrient solutions at 0, 50, 100, 500 and 1000 microM ZnS0(4). The results obtained show that Zn treatment is followed by a pathological behaviour, the precocity and intensity of which are dependent on the applied dose. In addition to the depressive effects on the biomass yield and the tissue water content, a decrease in the proteins contents was also observed. Zinc toxicity seems to induce synthesis of low molecular weight proteins in Zn-treated bean stems, but not in the roots and leaves. These peptides, in stems, may protect, hypothetically, the susceptibles metabolic sites in foliar parenchyma against the zinc deleterious effects.