Effects of Ni2+ during the early phases of radish (Raphanus sativus) seed germination

The effects of Ni2+ on Raphanus sativus seeds during the first 48 h of germination were investigated. Increasing concentrations of Ni2+ (0, 80, 100, 200 and 400 mu M) progressively inhibited the growth of radish seedlings. In parallel, Ni2+ affected the restoration of reabsorption of K+ and Mg2+ and the release of Ca2+ into the incubation medium. The transport mechanisms appeared to be well operative, as indicated by the negative values of the transmembrane electrical potential. Ni2+ strongly affected the reactivation of oxygen uptake and the increase in energy charge, the mobilisation of sugar and phospho-organic compounds and inhibited the synthesis of DNA, RNA and proteins. The presence of Ni2+ retarded the degradative and synthetic changes of protein of the soluble and microsomal fractions, occurring in seeds during germination; moreover, in both the soluble and microsomial fractions, two polypeptides from each were not expressed. (C) 1997 Published by Elsevier Science B.V.