Cytokinin affects nitrate reductase expression through the modulation of polyadenylation of the nitrate reductase mRNA transcript

Abstract Cytokinin (CK) and low-intensity light effects in modulating nitrate reductase (NR) activity, NR protein and NR encoding mRNAs were studied in tobacco cell suspension cultures. NR activity was strikingly enhanced by CK in dark- as well as in light-grown cells whereas it was less affected by light alone. NR protein accumulation was stimulated by the hormone in the light only; then a CK light-dependent regulation of NR activity was suggested. Light enhanced the steady-state levels of hybridisable total NR mRNA and a light-inductive effect was also observed after transfer from dark to light; this effect was dependent on sucrose supply and was enhanced in CK-supplied cells. NR poly(A) …