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Inheritance and expression of NAD(P)H nitrate reductase in barley.
R L Warner1, K R Narayanan, A Kleinhofs
1Department of Agronomy and Soils and Program in Genetics and Cell Biology, Washington State University, 99164-6420, Pullman, WA, USA.
Summary
Barley possesses two nitrate reductase types. The nar7 gene specifically controls NAD(P)H nitrate reductase in both leaves and roots, distinct from the NADH-specific enzyme.
Area of Science:
- Plant biochemistry
- Molecular genetics
Background:
- Barley (Hordeum vulgare L.) exhibits both NADH-specific and NAD(P)H bispecific nitrate reductases.
- Wild-type leaves contain only the NADH-specific enzyme, while nar1 mutants possess the NAD(P)H bispecific form.
Purpose of the Study:
- To identify and characterize the gene responsible for NAD(P)H nitrate reductase activity in barley.
- To elucidate the genetic control of nitrate reductase isoforms in barley leaves and roots.
Main Methods:
- Isolation and characterization of barley mutants deficient in nitrate reductase activity.
- Genetic analysis using crosses and segregation of progeny.
- Enzyme activity assays and differential inactivation studies.
Main Results:
- A double mutant (nar1a;nar7w) lacking NAD(P)H nitrate reductase activity was identified.
- The nar7 locus was identified as a single codominant gene controlling NAD(P)H nitrate reductase.
- nar7 is not closely linked to the nar1 locus and controls this activity in both leaves and roots.
Conclusions:
- The nar7 gene encodes the structural component of NAD(P)H nitrate reductase in barley.
- nar7 plays a crucial role in nitrate assimilation in both vegetative and root tissues.
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