2) Band 18 (former Band 3)
vs.15 (former Band 4'), and Band 1 (former Band 10) vs. Its absent.
Jones Fife is different from Chinese Spring in -amylase zymogram
pattern, i.e. lacking Bands 16, 18 and 21, and having added Bands 1,
1', 15 and 15' (Fig.2-b).
Bands 18 and 15 have been known to be allelic, coded by alpha-Amy-B1 and alpha-Amy-B1b,
respectively. Whereas Band 1 vs. its absent are controlled by alpha-Amy-B3a and alpha-Amy-B3b. Chromosome
complements and presence or absence of the respective bands were
scored on individual seed basis in BC1 of (CS ditelo 6BL x
Jones Fife) x CS (Table
3). Though four
plants with the unexpected chromosome complements, 41 and 40+t, two
plants each, occurred, these were treated as 42 and 41+t,
respectively, taking chromosome pairing at F1 meiosis into
consideration as in the previous case of Aka. From the results shown
in Table
3, recombination
values between centromere and two loci were estimated as follows:
Centromere -
alpha-Amy-B1
13.8 plus or
minus 2.6(%)
Centromere -
alpha-Amy-B3
5.5 plus or
minus 1.7(%)
alpha-Amy-B1
- alpha-Amy-B3
9.3 plus or
minus 2.2(%)
Thus, these loci are located as shown in
Fig.
3-b.
Gale et al. (1983) and Ainsworth (1985) reported one compound locus
of alpha-amylase isozymes on the long arm of each chromosome
belonging to homoeologous groups 6 and 7. In this study, however, we
confirmed evidently two loci of alpha-amylase as previously reported
by Nishikawa et al. (1981), and this agreed completely with Mukai
(1991), who clearly showed by in situ hybridization technique
two loci of alpha-amylase gene on the Ion. arm of chromosome 6B. It
seems evident that the signal on proximal segment corresponds to
alpha-Amy-B3, and the signal on distal segment to
alpha-Amy-B1.
3) Alpha-amylase loci in AABB tetraploid wheat.
Comparing with Chinese Spring, tetraploid wheat lacked, as expected,
those bands known to be controlled by the genes on chromosomes 6D and
7D. Ssp. georgicum once classified as species of Timopheevi
group, carried its specific bands 2, 10', 26 and 26' on one hand, and
lacked Bands 9 and 23 in comparison with durum LD 222, our
standard strain of AABB tetraploid. Moreover, major bands, 11, 16, 18
and 21 in LD 222, occurred as minor bands in georgicum
(Fig.2-c).
From the experiment using LD 222 doubleditelosomic for A and B genome
chromosomes, developed by the senior author, alpha-amylase isozyme
variation given above became evident to be attributable to the genes
on chromosome 6B, with an exception for Band 9, which seems to be
coded by the gene on 6A. In F2 plants between LD222 and
georgicum, recombination occurred neither between Bands 2, 26
and 26', nor between Bands 11, 16 and 21. Then, these bands are
treated tentatively as controlled by the respective compound loci.
Because Band 18 is coded by alpha-Amy-B1 in common wheat, the
compound locus for Bands 16, 18 and 21 is designated as
alpha-Amy-B1, though there is no direct evidence for their
homology, and the one for Bands 2, 26 and 26' as alpha-Amy-B5.
The gene for Band 10' which is designated as alpha-amy-B4
was also linked with 6BL.