> **Barley Genetics Newsletter 37: 34--36 (2007)**

Four new barley mutants

Sandra AI Wright^1^, Manochehr Azarang^2^, Anders B Falk^3^

^1^Dipartimento di Scienze Animali, Vegetali e dell'Ambiente, Facoltà di
Agraria, Università del Molise, Campobasso, Italy

^2^Maselaboratorierna, Uppsala, Sweden ^3^Department of Plant Biology
and Forest Genetics, University of Agricultural Sciences, Uppsala,
Sweden

**Introduction**

We screened a fast-neutron mutated barley population to isolate and
characterize barley lesion mimic mutants. The albino mutant frequency in
this population was found to be around 2%, suggesting that a
sufficiently high level of mutants could potentially be found. From a
screen of about 5000 M2 spikes, we found four mutants that were
characterized by the presence of necrotic or chlorotic leaf areas in the
form of spots or stripes. The four mutants were designated 1661, 2721,
3091 and 3550. The mutants were characterized with respect to their
visual appearance. In order to relate these mutants properly to
previously described barley lesion mimic mutants, we cultivated all
previously described barley mutants with aberrant leaf phenotypes (Davis
*et al.*. 1997) and compared the phenotypes to those of the newly
obtained mutants.

**Materials and Methods**

The near-isogenic barley line Bowman(*Rph3*) was obtained from Dr Jerry
D. Franckowiak, North Dakota, USA. It was constructed by introgression
of the *Rph3* resistance gene from the cultivar Estate into the cultivar
Bowman, and represents the 7th backcross. Mutation was performed with
fast neutrons at the International Atomic Energy Agency (IAEA), Vienna,
Austria, with a dose of 5 Gy. Five thousand M2 spikes were sown and the
mutant plants were screened for aberrant leaf phenotype. Selected
mutants were backcrossed twice to wildtype Bowman (*Rph3*), and their
phenotypes were analyzed using the backcrossed material. Plants were
grown either in a greenhouse or in caged outdoor compartments during the
summer. Experiments were done in controlled growth chambers at 22°C with
16/8 hours of light/darkness (long day conditions), or 8/16 hours of
light/darkness (short day conditions). Allelism tests were done as
inspections of leaf phenotypes of F1 plants resulting from crosses
between relevant mutants. An AFLP-based procedure was used to screen for
molecular markers linked to the mutants (Castiglioni *et al*. 1998).

**Results and Discussion**

Mutant 1661 displays chlorotic stripes (Figure 1). These stripes are
most pronounced on the first leaf. Under long day conditions, the
stripes do not appear on the later emerging leaves and the plants
eventually seem to recover from the phenotype conferred by the mutation.
Under short day conditions the mutation is semi-lethal since all leaves
develop the characteristic chlorotic stripes and the plants fail to
reach maturity and produce seeds. However, the phenotype initially
proves to be more severe under long day conditions. Mutant 1661 is
phenotypically similar to the previously described mutants mottled leaf
1 and mottled leaf 5, which have clearly marked white bands across the
leaves (Davis *et al*. 1997). Allelism tests indicated that 1661 is not
allelic to these. None of the pre-mapped Proctor-Nudinka AFLP markers
were linked to mutant 1661.

Mutant 2721 is characterized by chlorotic leaf spots and streaks that
coalesce and eventually form large white patches on the leaves (Figure
1). The phenotype is displayed on all leaves and as the leaves mature,
the white regions gradually become darker, seeming to undergo necrosis
and death. Often the necrosis affects the leaf edges, resulting in
wrinkled leaf edges. Under short day conditions, the leaf phenotype is
delayed by several days and is reduced in severity. Eventually all
leaves display the phenotype even under short day conditions. The mutant
initially appears to be similar to the mottled leaf 2 (Davis *et al*.
1997) and mottled leaf 6 (Franckowiak 2002) mutants, which display
yellow bands on the leaves. However, these mutants do not display the
necrosis of 2721. Allelism tests suggest that 2721 is not allelic to the
mottled leaf mutants. None of the pre-mapped Proctor-Nudinka AFLP
markers were linked to mutant 2721.

Mutant 3091 has brown spots towards the leaf tips and leaf edges,
particularly on the first leaf (Figure 1). Short days do not
significantly alter the phenotype. The leaf phenotype resembles those of
mutants *nec4* and *nec5* (Davis *et al.*. 1997). However, allelism
tests indicate that mutant 3091 is not allelic to either of these two.
For the mutation in 3091, linkage was detected to the AFLP marker
E37M33-6 on barley chromosome 3 (3H).

Mutant 3550 has conspicuous black or brown spots on the leaves (Figure
1). The spots usually do not coalesce. They appear on all above-ground
parts of the plant including the bristles. Mutant 3550 is delayed in
maturation and ripening, with seeds being ready for harvest about four
weeks later than in the wildtype. Short day conditions lead to a
slightly less pronounced phenotype. Mutant 3550 is similar to the *nec1*
mutant (Davis *et al*. 1997), but allelism could be ruled out due to
different mapping positions. The mutation in 3550 was localized on
chromosome 7 (5H). Linkage was detected to the AFLP markers E40M38-7,
E36M36-5, E42M36-14, E42M40-2 and E41M32-5.

References:

Castiglioni, P., Pozzi, C., Heun, M., Terzi, V., Müller, K.J., Rodhe, W.
and Salamini, F. 1998. An AFLP-based procedure for the efficient mapping
of mutations and DNA probes in barley. Genetics 149:2039--2056.

Davis, M.P., J.D. Franckowiak, T. Konishi, and U. Lundqvist, 1997. New
and revised descriptions of barley genes. Barley Genetics Newsletter 26:
22-516.

Franckowiak, J.D. 2002., BGS 629 Mottled leaf 6. Barley Genetics
Newsletter 32:170.

![](media/image1.wmf){width="6.3in" height="4.725in"}

**Figure 1.** Leaf phenotypes of the parent cultivar Bowman(*Rph3*) and
four lesion mimic mutants; 1661, 2721, 3091, 3550.