International Database for Barley Genes and Barley Genetic Stocks

BGS 637, NADH nitrate reductase-deficient 1 (EC1.6.6.1; Acc. No. X57844 and X57845), nar1

BGN  35:194
Stock number: BGS 637
Locus name: NADH nitrate reductase-deficient 1 (EC1.6.6.1; Acc. No. X57844 and X57845)
Locus symbol: nar1

Previous nomenclature and gene symbolization:



Monofactorial co-dominant based on enzyme assay (4).
Located in chromosome 6HS (2) in bin 6H-01 (3), nar1.a is about 0.8 cM proximal from molecular marker ABG466 (3).


Mutants are characterized by low in vivo nitrate reductase activity and low in vitro NADH nitrate activity. FMNH2 and cytochrome c reductase activity is variable among the different alleles. All mutants have elevated nitrite reductase activity and accumulate nitrate to variable degrees (1, 8). All nar1 mutants have normal xanthine dehydrogenase activity. All nar1 mutants are viable and morphologically normal except some alleles are slightly light green. Yields are slightly depressed (6). The mutant Xno29 (nar1.j) does not grow well in field plots probably due to other associated mutations (1).
No images

Origin of mutant:

A sodium azide induced mutant in Steptoe (CIho 15229) (4).

Mutational events:

nar1.a (Az12, GSHO 2413), nar1.b (Az13, GSHO 2414), nar1.c (Az23), nar1.d (Az28), nar1.e (Az29), nar1.f (Az30), nar1.g (Az31), nar1.h (Az32), nar1.i (Az33) in Steptoe (CIho 15229) (5); nar1.j (Xno29) in Winer (7); nar1.k (EMS29), nar1.l (EMS31) in Steptoe (5); nar1.m (Az56), nar1.n (Az57), nar1.p (Az63), nar1.q (Az64); nar1.r (Az65), nar1.t (Az67), nar1.ab (Az76), (Az77), (Az79), nar1.aj (Az80) in Steptoe (5); (BSMV1) in Vantage (CIho 7324) (1).

Mutant used for description and seed stocks:

nar1.a (Az12, GSHO 2413) in Steptoe


1. Kleinhofs, A. (Unpublished).

2. Kleinhofs, A., S. Chao, and P.J. Sharp. 1988. Mapping of nitrate reductase genes in barley and wheat. p. 541-546. In T.E. Miller and R.M.D. Koebner (eds.) Seventh Int. Wheat Genetics Symposium.

3. Kleinhofs, A., A. Killian, M.A. Saghai Maroof, R.M. Biyashev, P. Hayes, F.Q. Chen, N. Lapitan, A. Fenwick, T.K. Blake, V. Kanazin, L. Dahleen, D. Kudrna, J. Bollinger, S.J. Knapp, B. Liu, M. Sorrells, M. Heun, J.D. Franckowiak, D. Hoffman, R. Skadsen, and B.J. Steffenson. 1993. A molecular, isozyme and morphological map of the barley (Hordeum vulgare) genome. Theor. Appl. Genet. 86:705-712.

4. Kleinhofs, A., T. Kuo, and R.L. Warner. 1980. Characterization of nitrate reductase-deficient barley mutants. Molec. Gen. Genet. 177:421-425.

5. Kleinhofs, A., R.L. Warner, J.M. Lawrence, J.M. Melzer, J.M. Jeter, and D.A. Kudrna. 1989. Molecular genetics of nitrate reductase in barley. p. 197-211. In J.L. Wray and J.R. Kinghorn (eds.) Molecular and Genetic Aspects of Nitrate Assimilation, Chapter 13. Proc. 2nd Int. Symp. on Nitrate Assimilation - Molecular and Genetic Aspects, St. Andrews, July, 1987. Oxford Univ. Press, New York.

6. Oh, J.Y., R.L. Warner, and A. Kleinhofs. 1980. Effects of nitrate reductase deficiency upon growth, yield, and protein in barley. Crop Sci.20:487-490.

7. Tokarev, B.I., and V.K. Shumny. 1977. Detection of barley mutants with low level of nitrate reductase activity after seed treatment with ethylmethane sulphonate. Genetika (Moskva) 13:2097-2103.

8. Warner, R.L., C.J. Lin, and A. Kleinhofs. 1977. Nitrate reductase-deficient mutants in barley. Nature 269:406-407.


A. Kleinhofs. 2005. Barley Genet. Newsl. 35:194-195.