Ammonium and Amino Acids as Regulators of Nitrate Reductase in Corn Roots

Abstract

When amino adds or ammonia are added to plant systems, the effects on the development of nitrate-dependent nitrate reductase activity are variable. In addition, amino acids added singly or as casein hydrolysate may not support a normal growth. A physiologicafly correct mixture of amino acids, one similar in composition to amino acids released by the endosperm, has been shown to support normal growth and protein synthesis in corn (Zea mays) embryos. In this investigation, we have used the mixture of corn amino acids to determine whether amino acids have an effect on the appearance or disappearance of nitrate reductase activity. The results show that these amino adds partially inhibit the induction of nitrate reductase in corn roots. The effect is more pro-nounced in mature root than in root tip sections. When glutamine and asparagine are induded along with the "corn amino acid mixture," the