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A scst gene from T. timopheevi also
improved compatibility between the nuclear genome of durum wheat and
(lo) or (un) cytoplasm (Maan 1992a). The resulting
alloplasmic durum lines were male sterile, produced plump and viable
seeds having embryos with scst resulting in
28-chromosome male-sterile progeny, while seeds without
scst were shriveled and inviable The
scst gene is located on the long arm of chromosome 1A
(1AL) and closely linked with the centromere (Anderson and Maan 1995;
Maan et al. 1999). But, the scst gene was not
transferred to telo 1AL of Langdon durum by recombination in the
progeny of double-monotelosomic 1A F1's (dMt; 2n=29;
13"+t1t'") from crosses of (lo) scst;- durum
to double-ditelosomic 1A of Langdon durum (2n=30; 13''+2t''; dDt 1A)
nor misdivision of complete chromosome 1A produced telo 1AL with
scst in the progeny of 1A+1D double-monosomic (dM;
2n=28; 13"+2') F1's from a cross of (lo)
scst;- durum to 1D(A) double-disomic of Langdon.
Possibly, a gene or genes in the short arm of chromosome 1A (1AS) may
be essential for the functioning of scst in
1AL.
A vitality (Vi) gene of spontaneous origin located on 1BS
produced fertility in the (lo) durum lines carrying
scsae in 1DL on the 29-chromosome plants as well as
28-chromosome plants carrying scst on the complete
chromosome 1A (Maan 1992b). The Vi gene also produced fertile
(lo) durum or euplasmic durum lines having heterozygous or
homozygous scsae in T1AL. 1DL or T1BS. 1DL
translocation chromosome (Maan unpub).
Similarly, a scsspt gene from Ae. speltoides
produced compatibility between (vent) cytoplasm and
the nuclear genome of durum wheat (Maan unpub). The resulting
(vent) durum line was male sterile and when crossed to normal
durum produced plump and viable seeds having embryos with
scsspt, while female gametes without
scsspt did not function. The W gene did not produce
fertility in the (vent) scsspt durum,
indicating that scst and scsspt
differ in regards to interactions with the (lo),
(un), or (vent) cytoplasm, even though these
cytoplasms are similar to one another with regards to compatibility
with the nuclear genomes of durum or common wheat (Maan 1975,
1978).
In the progeny from successive crosses of (vent)
scsspt;- durum to normal durum, some of the plants
had pollen mother cells (PMC's) with a meiotic metaphase I
configurations (2n=28; 14" and 12"+1IV), indicating that
the (vent) durum carried a translocation chromosome (Maan
unpub). The objectives of this study were to identify the
translocation chromosome and determine the chromosomal location of
scsspt in the (vent) durum
line.
Materials and methods
A durum line (Selection 56-1) with a scsspt
gene from Ae. speltoids and cytoplasm from
Ae. ventricosa [(vent)
scsspt durum] was produced by S. S.
Maan at North Dakota State University, Fargo, ND (Maan unpub). A set
of 14 double-ditelosomics of Langdon durum (CS-LDN dDt) were produced
by Joppa (1988).
The (vent) scsspt durum, maintained by
crossing to durum Selection 56-1, was crossed to a set of 14 CS- LDN
dDt (2n=30; 13''+2t''). Some of the (vent)
scsspt durum plants were cytologically examined to
assure the presence of a translocation chromosome. The resulting
double-monotelosomic (dMt) F1's (2n= 29; 13''+t1t''') were
crossed to normal durum. Hybrid progeny were cytologically examined
to determine the meiotic chromosome number and chromosome pairing at
meiotic metaphase I in the pollen mother cells (PMC's).
The laboratory and greenhouse procedures were the same as described
by Maan et al. (1999). The experimental plants were g grown m a
greenhouse at Fargo, ND. The spikes of male-sterile plants were
covered with glycine bags prior to anthesis and recovered after
pollination to prevent out-crossing with stray pollen from other
wheat plants in the greenhouse.
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