Partitioning of reduced nitrogen derived from exogenous nitrate in maize roots: Initial priority for protein synthesis

Summary

When roots of five day-old maize seedlings were exposed to ¹⁵N-nitrate, a constant (25–29%) proportion of the reduced ¹⁵N derived from the entering ¹⁵N-nitrate accumulated as insoluble ¹⁵N nitrogen. Constancy was established by two hours and lasted through 12 hours at ambient ¹⁵N-nitrate concentrations of 0.05 mM to 20.0 mM. Even when little ¹⁵N nitrate had been reduced (> 2μmoles), there was a linear relationship between accumulation of insoluble ¹⁵N (but not accumulation or translocation of soluble reduced ¹⁵N) and total reduced ¹⁵N. It is proposed that protein synthesis from the entering nitrate occurs in close association with nitrate reduction.

Paper No. 9764 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC, 27695-7619, USA. This research was supported by Grant No. PCM-8118661 from the National Science Foundation.