Inhibition of nitrate reductase and ATPase activities in Zea mays roots by tungsten and N, N'-dicyclohexylcarbodiimide

Abstract

The activity of soluble and membrane-bound ATPase obtained from corn roots was in vivo markedly inhibited by N,N' -dicyclohexylcanbodiimide (DCCD) and W0₄^2- ions. DCCD (2.5 X 10^-5 M) added to the nutrient solution strongly decreased in vivo nitrate reductase (NR) activity after 12-h growth of plants while it had no effect in experiments in vitro on NR activity. Tungsten in a concentration of 10^-4 M completely blocked NR activity after 24 h. In the above used concentrations neither DCCD nor W0₄^2- inhibited completely N0₃^- absorption by corn roots. The results suggest that there must exist in corn roots another or an additional mechanism of N0₃^- assimilation apart from of that proposed by Butz and Jackson (1977).