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Effect of Ammonium, Sucrose and Light on the Regulation of Nitrate Reductase Level in Pisum sativum
Author(s) -
SIHAG R. K.,
GUHAMUKHERJEE SIPRA,
SOPORY SUDHIR K.
Publication year - 1979
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1979.tb01701.x
Subject(s) - cycloheximide , sucrose , ammonium , cordycepin , biochemistry , chloramphenicol , nitrate reductase , chemistry , pisum , enzyme , protein biosynthesis , organic chemistry , antibiotics
In shoot apices of 7‐day‐old dark‐grown peas the addition of ammonium along with the inducer nitrate resulted in a more than two‐fold increase in nitrate reductase activity. Individual amino acids, amides and amino‐acid mixture could not replace the ammonium effect. Ammonium also stimulated NADH‐glutamate dehydrogenase but not glucose‐6‐phosphate dehydrogenase. Sucrose caused a marked stimulation of nitrate reductase induction and showed synergistic effect with light. In presence of cordycepin and cycloheximide, induction of nitrate reductase was inhibited more if ammonium or sucrose was supplied along with the inducer. With actinomycin D, α‐amanitin or chloramphenicol, no differential inhibition took place in presence of ammonium. The inhibition of enzyme activity by chloramphenicol and 3‐(3,4‐dichlorophenyl)‐l,dimethyl urea was completely relieved by sucrose. Incorporation of 14 C‐lysine was markedly stimulated by sucrose, but was not affected by ammonium. The effect of sucrose and light on 14 C‐lysine incorporation was additive. Cordycepin and cycloheximide did not have any differential effect on 14 C‐lysine incorporation in the presence of ammonium as well as sucrose. The inhibition of 14 C‐lysine incorporation caused by chloramphenicol was relieved by sucrose. Sucrose also caused a marked increase in 3 H‐uridine incorporation but ammonium had no effect. Actinomycin D and cordycepin blocked the sucrose dependent increase in 3 H‐uridine incorporation. The results suggest that ammonium mediated stimulation may depend on a regulatory protein(s) synthesized in response to ammonium, whereas sucrose acts mainly by an overall increase in RNA and protein synthesis. The effect of light does not seem to be dependent on photosynthetic light reactions.