biologia plantarum

Biologia plantarum 43:79-84, 2000 | DOI: 10.1023/A:1026507114354

Differential Effect of Cd2+ and Ni2+ on Amino Acid Metabolism in Soybean Seedlings

F. El-Shintinawy¹, A. El-Ansary²

¹ Botany Department, Faculty of Science, Tanta University, Tanta, Egypt E-mail

² Laboratory of Medicinal Chemistry, National Research Center, Cairo, Egypt

In 10-d-old soybean seedlings, the growth of roots and shoots was significantly inhibited at 50 and 100 μM and more Cd²⁺, respectively, and by 50 μM or more Ni²⁺. Although total protein content of roots exposed to 200 μM Cd²⁺ or Ni²⁺ was similarly decreased compared to the control, the activity of nitrate reductase was much more inhibited by Cd²⁺. Ni²⁺-treatment (200 μM) induced an accumulation of all free amino acids in roots associated with a decrease in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities reflecting the accumulation of both alanine and aspartic acid, respectively. Cd²⁺-treatment (200 μM) decreased the amount of all free amino acids. In addition, cysteine which is the main amino acid consisting the phytochelatin complexes constituted about 17.5 % of total free amino acids. The activities of both ALT and AST in Cd²⁺-treated roots were higher than in Ni²⁺-treated roots suggesting higher conversion of alanine and aspartate to pyruvate and oxaloacetate. Primary leaves excised from either Cd²⁺ or Ni²⁺-treated seedlings showed similar pattern of enzyme activities as roots.

Keywords: alanine aminotransferase; aspartate aminotransferase; cysteine; Glycine max; heavy metals; HPLC; nitrate assimilation

Subjects: alanine aminotransferase, amino acid metabolism; aspartate aminotransferase, amino acid metabolism; cadmium, amino acid metabolism; cysteine, Cd, Zn, amino acid metabolism; Glycine max; heavy metals, amino acid metabolism; nickel, amino acid metabolism; nitrate reductase, amino acid metabolism; soybean, amino acid metabolism

Published: March 1, 2000  Show citation