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Genome analysis of Triticum georgicum
S. MATSUMURA, M. NEZU and Y. KOSHIBA
National Institute of Genetics, Misima. Japan
Many authors have taken an interest in the classification of Triticum
georgicum. When it was classified as a subspecies of T. Macha,
DEKAPRELEVICH and MENABDE (1932) have reported that it has 28 somatic
chromosomes. At present, it is assigned as a subspecies to T. dicoccum
by FLAKSBERGER (1939).
Morphologically, it is markedly different from other Emmer wheats, namely,
it has dense ear and the tops of the awns are not at the same level, and
on the other hand it resembles T. Macha and T. Timopheevi.
In order to make clear those relationships the authors have crossed T.
georgicum with the Emmer group and others, and cytologically analysed
the F1 hybrids. Particular attention was given to the chromosome
pairing in the meiosis of PMC. 1) T. georgicum x T. monococcum:
The F1 plants were obtained rather easily. The percentage of
cells having 6II+9I was 49%, and that of the secondary
5II+11I was 27%. Pollen- and seed-fertility was
very low. 2) T. georgicum x T. turgidum, T. durum
x T. georgicum: Of all crosses, the percentage of seed formation
was the highest in these 2 combinations. The chromosome pairing was very
regular, the percentage of cells having 14II was 98% in the
former case and 82% in the latter. The pollen- and seed-fertility was
as high as that of the parents. 3) T. georgicum x T. vulgare:
The hybrids were not easily obtained. As to chromosome conjugation, polyvalents
were rarely found, and the configuration 14II+7I
occurred in 82% PMC. 4) T. georgicum x T. Timopheevi: The
F1 hybrids were easily obtained, but the hybrids were very
poor, indicating an abnormal chlorophyll situation, and completely sterile.
Various configuration of chromosomes were found, namely cells with one
trivalent or 3 more amounted to 86%, and the configuration 12II+4I
occurred in 41% PMC. This finding is the same as KIHARA (1934). It seems
that the chromosomes of T. georgicum are not homologous to the
chromosomes of T. Timopheevi.
It is concluded from the above results that T. georgicum belongs
to the Emmer group. Its genome formula is AABB.
(Received May 20, 1958)
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