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Wheat Information Service
Number 93: 14-18 (2001)
Research article
An Aegilops speltoides-derived
scsspt gene located in T2BL.2S translocation
chromosome of durum wheat
S. S. Maan and S. F. Kianian
Department of Plant Sciences, North Dakota State University,
Fargo, ND 58104, U. S.A.
Summary
The nuclear genome of durum wheat (Triticum turgidum L.)
is incompatible with Aegilops ventricosa cytoplasm
[(vent) cytoplasm]. A species cytoplasm specific
(scsspt) gene from Ae. speltoides L.
improved nucleocytoplasmic compatibility and the resulting
(vent) durum line was male sterile and partially female
fertile. When crossed to normal durum, (vent) durum produced
28-chromosome plants with scsspt and a meiotic
metaphase I configuration indicating that some of the plants had a
translocation chromosome. Our objectives were to identify the
translocation chromosome and determine the chromosome carrying
scsspt. We crossed (vent) durum to a
set of 14 double-ditelosomics of Langdon durum, and crossed the
double-monotelosomic (dMt) F1's to normal durum, and
cytologically examined the hybrid progeny. Of the seven A-genome dMt
F1's, six (except dMt 4A) had two type of plants with
13''+t1t''' or 11''+1IV+t1t'''. Of the eight 6A dMt
F1's, five had 13''+t1t''', two had
11''+(1''')tIV+t', and one had 11'' +t(1''')tV,
while the progeny of dMt 2A included one plant with 12''+2t1'',
indicating that (vent) durum had a 2A.6A translocation.
Seven B-genome F1's had only 13''+t1t''' and produced
disomics and dMts from crosses to normal durum, while one (dMt2B)
produced only disomics, and one plant with a spontaneous maternal
telosome that remained unpaired with the paternal chromosome 2B
(2n=28; 13''+1'+t'). In summary, the (vent) durum has (a) two,
T2A.6A and T2B.2S, translocation chromosomes, (b)
scsspt is located in Ae. speltoides-derived
2S that is homoeologous to 2BS of durum, and (c) recombinants with
scsspt and durum chromosome 2B were not
obtained.
Key words: scsspt vs. Gc
genes, T2A. 6A and T2BL. 2S translocation chromosomes.
Introduction
The cytoplasms from several species of Aegilops, including
Ae. longissima, Ae. uniaristata, and Ae. ventricosa
[(lo), (un) and (vent)
cytoplasms, respectively] are fully compatible with the
nuclear genome of common wheat (Triticum aestivum L.)
(Maan 1975, 1978). The resulting common wheat lines were fertile and
used as the sources of alien cytoplasms to produce alloplasmic durum
wheat (T. turgidum L.) lines, because cytoplasmic genes have
exclusive maternal inheritance in the Triticeae species. The
(lo), (un) or (vent) durum lines, thus produced.
were male sterile and retained a long-arm telocentic of chromosome 1D
(telo 1DL) from common wheat. Telo 1DL has a species cytoplasm
specific (scsae) gene that improves compatibility
between these cytoplasms and nuclear genome of durum wheat (Tsuji and
Maan 1981; Maan and Endo 1981, 1991). The resulting 29-chromosome
male-sterile lines when crossed to normal durum produce plump and
viable seeds having embryos with 1DL yielding 29-chromosome
male-sterile progeny, while the fertilization of 14-chromosome female
gametes without 1DL (scsae) by 14-chromosome male.
gametes of normal durum produce shriveled and inviable seeds. Telo
1DL remained unpaired during meiosis in 29-chromosome plants, and
therefore, scsae in 1DL was not transferred to a
durum chromosome. Male-sterile lines with a T1AL.1DL (Maan et al.
1999) or T1BS.1DL translocation chromosome carrying
scsae have been obtained (Maan unpub).
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