Effects of hexavalent chromium on maize, tomato, and cauliflower plants

The research presented in this paper was undertaken to study the short term response to hexavalent chromium [Cr(VI)] in seeds (caryopses), roots, and leaves of Zea mays, Lycopersicon esculentum, and Brassica oleracea, mainly in terms of ultrastructural alterations, Cr vacuole accumulation, and production of phytochelatins Following a Cr(VI) treatment at concentrations of 5 and 10 mg 1(-1), the percentage of germination did not differ significantly between treated material and controls in all the species examined. However, Cr(VI) supply caused a decrease in the growth rate of the primary root and also a strong inhibition in the shoot growth. By means of transmission electron microscopy and X-ray microanalysis, we observed several ultrastructural alterations of the treated material and the presence of electron-opaque precipitates, containing Cr, in the leaf tissue. In tomato plants treated with Cr(VI), no production of phytochelatins was detected either in roots or in leaves. Conversely, glutathione levels ranged from about 30 nmol SH g(-1) FW of root extracts to 300 nmol SH g(-1) FW of leaf extracts.