A Database for Triticeae and Avena
II.10. Barley haploid studies.
K. J. Kasha, E. Reinbergs, W. A. Johns, N. C. Subrahmanyam and K. M.
Ho. Department of Crop Science, University of Guelph, Guelph, Ontario,
The barley genetic studies at Guelph are closely associated with the
breeding program and the haploid project is one good example of this. The
cytogenetic studies (K. J. Kasha) are being conducted on materials from
the breeding program (E. Reinbergs). Thus, the doubled haploids resulting
from genetic and cytological studies of haploid formation and development
are being evaluated for potential varieties or for obtaining information
on breeding techniques. Following are three brief outlines of thesis projects
that are in progress. In addition, Dr. E. J. Walsh has just begun a Post-doctorate
Fellowship project in the area of breeding techniques with the doubled
1. Haploids in barley breeding. W. A. Johns
The purpose of this study is to compare haploids with the bulk and
pedigree methods of barley breeding for both qualitative and quantitative
characters. Homozygous doubled haploid lines are being produced from F1
hybrids (Dr. Kasha's program) and will be compared under field conditions
with the parental cultivars and recommended commercial varieties. Materials
from the same crosses will be handled by the bulk and pedigree methods.
Preliminary field observations on doubled haploids in 1970 and 1971
revealed the striking uniformity of the lines. Qualitative characters were
simple to detect. In 1971, a total of 65 doubled haploid lines from two
crosses were grown in single-row 10' plots along with randomly selected
F3's. Parental cultivars were placed as checks in every 3rd row.
Frequencies of lines with rough vs. smooth awns, two-rowed vs. six-rowed
spikes and disease resistance indicated that a random sample of genotypes
was obtained following "gamete selection" from F1 hybrids. Sufficient seed
from 19 unselected doubled haploids permitted a replicated yield test to
be run in 1971. Four of the doubled haploids in this test significantly
outyielded the parental lines and two other commercially recommended varieties
that were included. Other quantitative characters have not been analyzed
In 1972 we expect to have a total of 400 doubled haploids from three
different crosses under field evaluation. In addition, the F4 rows and
bulks from F3 rows will be grown. Replicated yield tests will be conducted
to compare the most promising doubled haploids with parental lines and
2. A cytological study of chromosome elimination during haploid formation
in barley N. C. Subrahmanyam
Numerous haploids of cultivated barley have been produced from the cross
of Hordeum vulgare (2n=14) by H. bulbosum (2n=14), Dihaploids
(2n=14) can also be produced by crossing the tetraploid (2n=28) cytotypes
of vulgare and bulbosum. However, the cross diploid vulgare
(2n=14) by tetraploid bulbosum (2n=28) usually gives a stable triploid
Reports of Kao and Kasha (1969), Kasha and Kao (1970), Symko (1969)
and Lange (1969, 1971) independently suggested the hypothesis of chromosome
elimination as a mechanism leading to haploidy in barley. Kasha and Kao
(1970) suggested that the genome balance between the parental species was
important in chromosome stability. The present study aims to trace the
process of chromosome elimination in tissues (embryo and endosperm) with
different genomic constitutions, The following table presents different
cross combinations and assuming fertilization, the expected genomic constitutions
of embryo and endosperm which are being used for cytological examinations:
Squash preparations of embryo and endosperm are being made to determine
the frequencies of cells with different chromosome numbers and abnormalities.
Table 2 presents mainly chromosome variations in the embryos of VB constitution.
The process of chromosome elimination appears to be gradual and the elimination
can occur at any time after fertilization. The percentage of cells with
7 chromosomes (haploid set) increases with the age of the embryo while
the percentage of abnormalities (extranuclear material, dense staining
bodies, etc,) decrease. From the same cross endosperm cells with the expected
VVB genomic constitution were quite variable in chromosome number, ranging
from 14 to 28.
Table 2. Chromosome variations and abnormalities
in embryos with VB constitution.
In embryos from a reciprocal cross between the diploid parents a similar
pattern of chromosome elimination was observed. However, in this cross,
the endosperm with BBV constitution appeared to have cells with relatively
few abnormalities and with more stable chromosome numbers. Even at 7 days,
most dividing cells had 21 chromosomes.
Embryos VBB genomic constitution were mostly stable and all the seedlings
obtained from this cross combination had stable chromosome numbers (2n=21).
Thus it is quite evident that chromosome or genome balance in the hybrids
is important. Furthermore, techniques which would speed up the elimination
of bulbosum chromosomes might lead to higher frequencies of haploids
following embryo culture.
Kao, Ko N., and Kasha, K. J. 1969. Haploidy from interspecific crosses
with tetraploid barley. Proc. 2nd Int. Barley Genet. Symp. II: 82-88.
Kasha, K. J. and Kao, K. N. 1970. High frequency haploid production
in barley (Hordeum vulgare L.). Nature 225:874-876.
Lange, W. 1969. Cytogenetical and embryological research on crosses
between Hordeum vulgare and H. bulbosum. Versl. landbowk.
Lange, W. 1971. Crosses between Hordeum vulgare L. and H.
bulbosum L. II. Elimination of chromosomes in hybrid tissues. Euphytica
Symko, S. 1969. Haploid barley from crosses of Hordeum bulbosum
(2x) X H. vulgare (2x). Can. J. Genet. Cytol. 11:602-608.
3. Genetic control of chromosome elimination during the formation of
barley haploids. K. M. Ho
The results from all the possible interspecific crosses between H.
vulgare and H. bulbosum (both diploid and tetraploid forms)
revealed that to obtain chromosome stable hybrids the genomes of H.
vulgare and H. bulbosum should be in a 1 to 2 ratio (Kao and
Kasha, 1970). However, a hybrid with 27 chromosomes was occasionally produced
from the cross between tetraploid forms of these two species, indicative
that a specific chromosome(s) may carry factor(s) controlling chromosome
stability in these interspecific hybrids (Kasha et al., 1970).
To test this hypothesis, crosses between the seven primary trisomic
types of diploid H. vulgare and the autotetraploid form of H.
bulbosum are being carried out.
Such crosses are expected to produce two types of hybrid progeny, a)
21 chromosome triploid hybrids and b) 22 chromosome hybrids (3x+1) when
the trisomic chromosome is transmitted. The frequency of 22 chromosome
hybrids should be similar to the trisomic transmission frequency in diploid
vulgare. If specific chromosomes carry a factor(s) controlling chromosome
stability, the 22 chromosome hybrids will not occur or be rare in crosses
with plants trisomic for that chromosome. In such instances one might expect
to find 8 chromosome haploids (X+1) if they are able to survive.
The preliminary results of crosses between primary trisomics of H.
vulgare and the tetraploid form of H. bulbosum are given in
Table 3. The results show that the frequency of 22 chromosome hybrid progeny
is low from crosses involving chromosomes 2 and 3, being 1.8 and 5.3% respectively.
However, 8 chromosome progeny have not been found to date.
Table 3. Progeny from crosses between primary trisomics
of diploid H. vulgare and tetraploid H. bulbosum.
It would appear that chromosome 2 and possibly chromosome 3 contain
major genetic factors which are critical to the chromosome balance and
stability in the interspecific hybrids between H. vulgare and H.
bulbosum. Additional crosses using telotrisomics for chromosomes 2
and 3 will be conducted.
Kao, K. N., and K. J. Kasha. 1970. Haploidy from interspecific crosses
with tetraploid barley. Barley Genetics II:82-89. Kasha, K. J., K. N.
Kao and E. Reinbergs. 1970. Genetic control over chromosome stability
in hybrids from interspecific Hordeum crosses. Genetics 64(2):33s.
BGN 2 toc
BGN Main Index