Abstract
Nitrate reductase (NR)-deficient mutants of cultured spinach cells were selected by chlorate resistance. Two mutants (12F and I-1 cell lines) were isolated and analyzed for activities, protein levels, and the expression of mRNAs of NR and nitrite reductase (NiR). When mutant cells were transferred to a medium containing 20 mM KNO 3 and 20 mM NH 4 NO 3 as a nitrogen source, the 12F cell line had no detectable NR activity or NR protein, but the NR mRNA was expressed clearly in contrast with the data of activity and protein levels. The NiR activity and protein were still induced and the NiR mRNA was also expressed clearly. In the I-1 cell line, however, the NR activity and protein were still present at low levels, and the NiR activity and protein were no longer inducible. Extremely low levels of the NR and NiR mRNAs were found in the I-1 cell line. These results suggest that the 12F and I-1 cell lines are structural gene mutant and regulatory gene mutant, respectively.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call