TITLE:
Cadmium Effects on Enzymes of Ammonia Assimilation in Excised Etiolated Maize Leaf Segments during Greening: A Mechanistic Approach
AUTHORS:
Juliana Sarangthem, Sonal Dhamgaye, Rekha Gadre
KEYWORDS:
Glutamine Synthetase, Cd Effects, Ammonia Assimilation, Zea mays, Maize Leaves
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.6,
May
26,
2017
ABSTRACT: Supply
of CdCl2 in the presence of NH4NO3 to excised
etiolated maize leaf segments during greening decreased the glutamine
synthetase and nicotinamide adenine dinucleotide reduced (NADH) dependent
glutamate synthase activities, while the ferredoxin (Fd) dependent glutamate
synthase and glutamate dehydrogenase activities were increased. Inclusion of
inorganic nitrogen, metabolites and the inhibitor influenced the effect of Cd
on glutamine synthetase activity. The % inhibition of activity caused by Cd was
higher with NO3- but lower with NH4+. Glutamine, 2-oxoglutarate, glutathione and sucrose decreased the %
inhibition by Cd with the more prominent effect with glutamine and sucrose.
Methionine sulfoximine exerted a more
prominent effect for + Cd enzyme at lower concentration. The results indicate
the involvement of reciprocal effects of Cd on glutamine synthetase and
glutamate dehydrogenase activities and also on NADH- and Fd-glutamate synthase
activities. For the inhibitory effect of Cd on glutamine synthetase activity, NH4+, glutamine, 2-oxoglutarate, glutathione and sucrose exerted a protective
effect with the sucrose being most effective.