Mutants are characterized by low in vivo nitrate reductase activity and low in vitro NADH nitrate reductase 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 degree (4, 5). All nar1 mutants have normal xanthine dehydrogenase activity. All of the nar1 mutants are viable and morphologically quite normal except that some alleles are slightly light green. Yields are slightly depressed (6). The mutant Xno29 (nar1j) does not grow well in field probably due to other associated mutations.
nar2
Mutants are characterized by pleitropic loss of nitrate reductase and xanthine dehydrogenase activity due to defective molybdenum cofactor synthesis or insertion. Some of the alleles are viable (nar2a; Az34), but have a definite light green color and loss of vigor. The nar2ad and nar2ag (R9401 and R9201) homozygotes are not viable and are best maintained as heterozygotes.
nar3
Description: Mutants characterized by pleiotropic loss of nitrate reductase and xanthine dehydrogenase activity (3). Mutants Xno18 and Xno19 (nar3a and nar3b) and Az71 (nar3x) are lethal.
nar4
Mutant is characterized by pleiotropic loss of nitrate reductase and xanthine dehydrogenase activity (3). It is lethal in the field, but can be grown to maturity in the greenhouse with a reduced nitrogen source.
nar5
Mutants are characterized by pleiotropic loss of nitrate reductase and xanthine dehydrogenase activity (3). All alleles are somewhat light green and viable.
nar6
Mutant is characterized by pleiotropic loss of nitrate reductase and xanthine dehydrogenase activity (3). The homozygote is not viable and is best maintained as a heterozygote.
nar7
Mutant lacks root NAD(P)H-bispecific nitrate reductase activity. All other nitrate reductase associated activities, xanthine dehydrogenase and nitrate reductase are normal. Morphologically the mutant is viable and appears normal in all respects.
nar8
Mutant is characterized by pleiotropic loss of nitrate reductase and xanthine dehydrogenase activity (3). The homozygote is not viable and is best maintained as a heterozygote.
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Steptoe x Az212
Mutant is lacking ligules, but has rudimentary auricles which clasp the stem in a displaced (not symetrical) manner. The plant is semi-dwarf with a distorted head type. Mutation is easily identified at all growth stages.
Mutant mo6b has four carpels and two leaf like structures. Stamens and lodicules are absent. It is presumed that the three stamens found in wild-type flower have been converted to three additional carpels and that the lodicules have been converted to the leaf like structures. The plant appears to be normal, but is completely sterile. This mutant appears to be similar to mo5 and maps to approximately the same region (2). Seed of mo5 were not available for allelism testing.
Mutant mo7a flower has between five and seven abnormal-appearing carpel-like structures and normal-appearing lodicules. Stamens are not present, but some of the carpels are sometimes terminated in stamen-like structures. Color photographs may be viewed at http://barleygenomics.wsu.edu click on "developmental mutants". The plant is somewhat abnormal with a twisted and compacted spike and reduced length awns. Pollination with wild-type pollen results in a few seeds. The mo7a mutant appears to be similar to mo1 and mo3 (2, 3), but seed of these mutants was not available for allelism testing.
The mutant floret has two carpels and two anthers and two lodicules. It appears that one of the anthers has been converted to a carpel. However, this does not occur in all florets. The florets with two carpels often set two seeds (1). This is a difficult trait to work with.
Stigma is present, but completely lacking hair structures. Mutant shows partial sterility that is due to absence of stigma hairs and therefore presumably poor capture of the pollen by the stigma. Otherwise, the mutant appears to be normal.
Mutant plants look normal except that the spike is very rudimentary or missing completely. Occasionally a few florets are formed, but they are mostly sterile.
Mutant appears very normal except that it has a very rudimentary carpel that is female sterile. The pollen appears to have normal fertility.
Mutant appears very normal except for a very bushy spike due to the many awn-like structures. The flower lacks all reproductive tissues and is completely sterile.
Mutant is extremely sensitive to smut. The head becomes entirely smut covered under Pullman, WA field conditions where smut is rare and, if it does occur, confined to one or a few florets.
Mutants grow very prostrate and do not head until very late in the season, sometimes not at all.
Mutant spike develops normally except that there is no seed set in the tip. It may appear as an environmental problem at first, but all spikes exhibit the trait and it is inherited.