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Wheat Information
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Number 76: 63-66
(1993)
Genome
structure of tetraploid wheats revealed by fluorescence in
situ hybridization using total genomic DNA
probes
Y. Mukai
Laboratory of Plant Molecular Genetics, Division of Natural
Science, Osaka Kyoiku University, Kashiwara, Osaka 582, Japan
Introduction
Tetraploid wheats can be classified into two groups: the emmer
wheats (genome = AABBDD) and the timopheevi wheats (AAGG). Both
tetraploids received their A genome from the einkorn wheats. Although
the origin of B and G genomes is under discussion, Aegilops
speltoides is most suitable for both B and G genome donors
(Tsunewaki et al 1980, Dvorak and Zhang 1990). In this study the
relationship of tetraploid wheats and their putative diploid species
was analyzed with respect to the genome structure by fluorescence
in situ hybridization (FISH) using total genomic DNA probes of
the diploid species. This paper provides molecular cytogenetic
evidence for translocation between different genomes.
Materials and methods
Four tetraploid species, Triticum dicoccoides (AABB),
T. dicoccum (AABB), T. araraticum (AAGG) and
T. timopheevi (AAGG) and two diploid species, T.
monococcum (AA) and Ae. speltoides (SS) were used in
the present study. The genomic in situ hybridization (GISH)
analysis was carried out as described by Mukai and Gill (1991) and
Mukai et al (1993). Total genomic DNA from T. monococcum
or Ae. speltoides was used as a probe. The other total
genomic DNA was used as a blocking DNA at eight times the probe
concentration. The sites of hybridization of biotinylated probe were
detected using avidin-FITC.
Results and discussion
FISH analysis using total genomic T. monococcum DNA
The FISH patterns of T. dicoccoides and
T.dicoccum showed that the A genome chromosomes were labeled by
yellowish green fluorescence, while the B genome chromosomes revealed
little fluorescence. In both species one translocation between
genomes was detected. The distal 34% of the long arm of chromosome 4A
was derived from a B genome chromosome.
The FISH patterns of T. araraticum and T. timopheevi
showed that the biotin label was seen on all A genome chromosomes
and two G genome chromosomes (Fig.1).
Three translocations between two genomes were detected. Chromosomes
involved in the translocation were 6A, 1G and 4G. In chromosome 6A,
one third of the short arm and a satellite including NOR came from
the G genome. Chromosome 1G showed an intercalary translocation. A
small segment of the A genome chromatin is inserted in the
interstitial region of the 1G short arm. The other A genorne
chromatin is present in the distal part of the 4G short arm.
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