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Wheat Information
Service
Number 85: 45-46 (1997)
Research information
Screening
of spontaneous translocations in cultivated Emmer wheat
T.
Kawahara
Laboratory of Crop Evolution, Graduate School of Agriculture,
Kyoto University, Mozume, Muko, Kyoto 617, Japan
Although many spontaneous translocations have been reported in
tetraploid Emmer wheat (Nishikawa et al. 1986; Schlegel 1996), the
overall frequency of rearranged types is unknown. In this study, the
translocations in cultivated Emmer wheat was screened and the
translocation frequency was estimated.
Twenty five strains of cultivated Emmer wheat were intercrossed and
chromosome pairings were observed in F1 hybrids (for
strain number, see Table
1 ).
They consist of 6 strains of Triticum dicoccum Schubl., 5 of
T. durum Desf., 4 of T. carthlicum Nevski, three each
of T. abyssinicum Vav. and T. Paleocolchicum Men and
one each of T.
orientale Perc., T. polonicum L., T. pyramidale (Del.)
Perc. and T. turgidum L. (for detailed passport data, see
Tanaka 1983). Several translocation tester strains of wild Emmer
(Taketa and Kawahara 1996), T. dicoccoides Korn. were also
used in the crossings. The chromosome pairings of the hybrids were
observed at the first meiotic metaphase of the pollen mother cells by
the aceto-orcein squash method.
The strains examined were classified into four groups based on the
presence or absence of translocations; those without translocations
(E1a type), and those with one (E7 type) and two translocations (E21
and E22 type) as shown in Table
1 .
Three strains with one translocation were intercrossed and the
hybrids showed normal meiosis with 14 bivalents. They were then
crossed with the translocation testers, E2 to E6, of T.
dicoccoides and pairings were observed as shown in
Table
2. Since this
translocation is different from those already found in T.
dicoccoides, the rearranged chromosome structure was named E7
type. One of the two strains with two translocations, KU-185, shared
one translocation in common with the E7 type (Table
2) and was called
the E21 type. The other, KU-111, had two different translocations
from E21 (detailed data not shown) and was named E22. The present
results are in agreement. with those obtained by Nishikawa et al.
(1986). From the chromosome pairing among strains and the detailed
information on strains used, the types reported by Nishikawa et al.
(1986) corresponded to those used in this study. Chromosomes involved
in translocations of wild and cultivated Emmer wheat have been
identified by using telosomics or Cbanding (Nishikawa et al. 1986;
1994, Taketa and Kawahara 1996) and the available data are summarized
in Table
3. Observed
multivalents shown in Table
2 are in
agreement with those expected from Table
3.
The standard type, E1a, was found in both wild and cultivated Emmer
but E2 to E6 in wild type only and E7, E21 and E22 in cultivated
form. All three strains of T. abyssinicum, KU-185, 186
and 188, had a common 2A-4B translocation, suggesting the fixation of
this structural rearrangement in T. abyssinicum.
In summary, of 25 strains examined 20 were of the standard type,
three had one translocation and two had two translocations. The
average number of translocations (total number of translocations
detected/number of strains examined) in cultivated Emmer wheat was
0.280. This is in good agreement with that of 0.202 reported for
Israeli wild populations of T. dicoccoides (Kawahara
and Nevo 1996). Therefore, the present value can be regarded to be a
good estimation of the frequency of spontaneous chromosomal mutation
in cultivated Emmer.
References
Kawahara T and Nevo E (1996) Screening of spontaneous major
translocations in Israeli populations of Triticum dicoccoides
Korn. Wheat Inf Serv 83: 28-30.
Nishikawa K, Takagi A,
Ban T, Otsuka H and Furuta Y (1986) Spontaneous reciprocal
translocations in cultivated form of Emmer wheat. Jpn J Genet
61:361-370.
Nishikawa K, Mizuno S and
Furuta Y (1994) Identification of chromosomes involved in
translocations in wild Emmer. Jpn J Genet 69: 371-376.
Schlegel R (1996) A
compendium of reciprocal translocations in wheat: 2nd Edition. Wheat
Inf Serv 83:35-46 Taketa S and Kawahara T (1996) C-banding analysis
on wild Emmer (Triticum dicoccoides Korn.) strains with and
without spontaneous reciprocal translocations. Theor Appl Genet 92:
173-178.
Tanaka M (1983) Catalogue
of Aegilops-Triticum germ-plasm preserved in Kyoto University.
Plant Germplasm Inst Fac Agric Kyoto Univ: 1-179.
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