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Production of wheat x barley hybrids
and preferential elimination of barley chromosomes
T. Koba, T. Handa and T. Shimada
Research Institute of Agricultural Resources, Ishikawa
Agricultural College, Nonoichi, Ishikawa 921, Japan
In order to introduce early heading and/or early maturing
traits of barley, Hordeum vulgare L., into common
wheat, Triticum aestivum L., we produced barley x
wheat hybrids (Shimada et al 1987). However, pistillody and
low female fertility were found in the backcrossed
generations by wheat, probably due to interaction between
nucleus and barley cytoplasm. Thus, we decided to produce
wheat x barley hybrids, though the cross is reported to be
more difficult than the barley x wheat cross (Fedak 1980;
Islam et al 1981).
In the winter of 1987-1988, intergeneric crosses were
carried out using four wheat cultivars and four barley
cultivars (strains) (Table 1) in a
greenhouse under 15-25C and long day photoperiod conditions.
Two days prior to pollination, emasculation and injection of
100mg/l 2,4-D to wheat stems were carried out.
Crossabilities (no. of embryos obtained/no. of florets
pollinated) were different among the cross combinations
between wheat and barley cultivars (Table
1). Among wheat cultivars, Norin 12, Norin 61 and
Shinchunaga showed extremely higher crossabilities than that
of Chinese Spring. Since Chinese Spring and Shinchunaga are
known to have kr1kr2 genes (Sasaki 1987), this result
suggests that the crossability between wheat and barley is
controlled by the gene(s) other than kr. Clear
difference was also found among barley cultivars in the male
side, i.e., Betzes barley showed the highest crossability to
wheat. Thus, the cross Norin 12 x Betzes showed the highest
crossability in this experiment and it was higher than those
reported previsouly (Fedak 1980; Islam et al 1981).
The embryos were rescued by culture on N6 medium
supplemented with 0.5mg/l GA3, 0.5mg/l IBA and
400mg/1 Casein Hydrolysate at 14-20 days after pollination,
and then 74 plants were obtained.
Chromosome number variation was observed in the root tip
cells of the 60 seedlings of the hybrids. Among them, 28
seedlings had 28 chromosomes, as expected, comprizing of 21
wheat and seven barley chromosomes, and eight seedlings has
21 chromosomes which were assumed to be haploids of wheat.
The other 23 seedlings were aneuploid hybrids which had
22-27 chromosomes and one had 29 chromosomes. About half of
the aneuploid hybrids showed mosaic chromosome number.
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