A Database for Triticeae and Avena
III.4. Maintenance and efficient use of lethal seedling mutations
T. Tsuchiya, Department of Agronomy, Colorado State University, Fort
Collins, Colorado 80521, U.S.A.
*This research was partly supported by NSF Research Grant GB30493 and
Colorado State University Experiment Station Project (Hatch 8).
It has been a problem to maintain genetic stocks for lethal seedling
mutations and to use them in genetic and linkage studies, unless the heterozygotes
can be identified.
Ogawara and Hayashi (1964) reported the method of breaking dormancy
or germinating prematured seeds before entering dormant stage.
The methods described by Ogawara and Hayashi (1964) have been applied
to the maintenance and efficient use of lethal seedling mutations in genetic
studies in barley with considerable success. This method is also used to
speed up experiments by germinating F1 and F2 seeds in premature stages.
This article describes the method used with some results obtained. More
than 3000 seeds from 131 plants of 26 lethal chlorophyll mutant stocks,
418 crossed seeds (F1 combinations) and 2781 seeds of F2 generations from
57 cross combinations were used in these experiments. The materials were
grown in the greenhouse in the winter of 1971-1972. The young seeds 26
to 40 days after pollination (as early as soft dough to as late as hard
dough stages) were harvested, immediately dehusked, cut in half, placed
on wet germination paper in germination boxes which were placed in a cold
room (temperature 2° to 4° C) for 3 to 7 days. The seeds are taken
from the cold room and placed in a room at ordinary temperature (20-23°
C). Germination resulted in 3 to 4 days. In Table 1 is a summary of results.
Table 1. Germination percentage of immature seeds
treated as mentioned in the text.
The results showed that the germination percentage was very high and
was comparable to that for seeds stored for 2-3 months after harvesting
at complete maturity.
This method is extremely useful for allelism testing of seedling mutations
that are either lethal or viable such as white streak, yellow streak, glossy
This method of germinating immature seeds was also used in selecting
heterozygous plants for intercrossing of lethal seedling mutants. Flowering
date of the first spike was marked on a tag attached to the plant. About
26 to 35 days after pollination seeds were germinated by the above described
procedure and tested for normal homo or mutant hetero condition. Normal
homo plants were discarded and only the mutant hetero plants were used
for crossing. In this way it has become possible to conduct trisomic analysis
and allelism testing with lethal seedling mutants much easier than ever
For the maintenance of these stock, it has become possible also to handle
the materials just like viable homozygotes: After finding the normal homo-
and mutant hetero-plants all normal homozygotes are discarded, all heterozygotes
are saved to grow to maturity. These heterozygotes are harvested and threshed
in bulk similar to viable stocks.
This technique can be used not only for lethal chlorophyll mutations
but also for other lethal seedling mutations such as minmin for
Ogawara, K. and J. Hayashi. 1964. Dormancy studies in Hordeum spontaneum
seeds. Ber. Ohara Inst. Landw. Biol. 12:159-188.
BGN 2 toc
BGN Main Index