biologia plantarum

Biologia plantarum 46:105-109, 2003 | DOI: 10.1023/A:1027393201387

The Role of Ammonium Assimilating Enzymes in Lentil Roots and Nodules

J. Chopra¹, N. Kaur¹, A.K. Gupta¹

¹ Department of Biochemistry, Punjab Agricultural University, Ludhiana, India

Activities of ammonium assimilating enzymes glutamate dehydrogenase (GDH), glutamine synthetase (GS), glutamate synthase (GOGAT), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) as well as the amino acid content were higher in nodules compared to roots. Their activities increased at 40 and 60 d after sowing, with a peak at 90 d, a time of maximum nitrogenase activity. The GS/GOGAT ratio had a positive correlation with the amino acid content in nodules. Higher activities of AST than ALT may be due to lower glutamine and higher asparagine content in xylem. The data indicated that glutamine synthetase and glutamate synthase function as the main route for the assimilation of fixed N, while NADH-dependent glutamate dehydrogenase may function at higher NH₄ ⁺ concentration in young and senescing nodules. Enzyme activities in lentil roots reflected a capacity to assimilate N for making the amino acids they may need for both growth and export to upper parts of the plant.

Keywords: alanine aminotransferase; aspartate aminotransferase; glutamate dehydrogenase; glutamate synthase; glutamine synthetase; Lens culinaris

Subjects: alanine aminotransferase; ammonium assimilating enzymes; aspartate aminotransferase; glutamate dehydrogenase; glutamine synthetase; Lens culinaris (Lens esculenta); lentil, ammonium assimilating enzymes; root, nodules, ammonium assimilating enzymes

Published: July 1, 2003  Show citation