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II. Proceedings of the 15th Wheat
Genetics Symposium of Japan
The 15th Wheat Genetics Symposium of Japan was held on April
5, 1989 at Yokohama, Japan, chaired by Dr. M. Tanaka under
sponsorship of Kihara Institute for Biological Research.
Seventy-eight wheat researchers attended the symposium with
hot discussions. The followings were the abstructs of the
presentations. Addition to the research reports, Drs. M.
Tanaka and S. Sakamoto introduced a slide presentation on
the Botanical Expedition to Tibet in summer, 1988.
Phylogeny of wheat and its relatives as
viewed from nuclear, chromosomal and chromosome arm DNA
content
Y. Furuta
Faculty of Agriculture, Gifu University. Gifu, 501-11,
Japan
Bhaskaran and Swaminathan (1960), Pai et al (1961), Upadhya
and Swaminathan (1965) emphasized the diminution of
chromosome length and nuclear DNA content in connection with
polyploidy in wheat. However, Rees (1963), and Rees and
Walters (1965) could not detect such diminution. In relation
to the functional diploidization in polyploid and phylogeny
of wheat, DNA content per nucleus of single-layer smeared
pollen tetrad in wheat and its relatives, DNA content of
individual chromosome at the first meiotic metaphase in
hexaploid wheat and individual telocentric chromosome in
mitotic root tip cell of common wheat were measured
Feulgen-cytophotometrically. The results are summarized as
follows:
1. Nuclear DNA content in di-, tetra- and hexaploid wheat is
not simple ratio of 1:2:3, but 1.0:1.6:2.4 (Nishikawa and
Furuta 1969).
2. There is no intraspecific variation in Triticum
monococcum (Furuta et al 1978), T. urartu (Furuta
et al 1986) and T. aestivum (Nishikawa and Furuta
1967).
3. T. aestivum has the sum of DNA of T.
turgidum and Aegilops squarrosa (Nishikawa and
Furuta 1969. Furuta et al. 1974), indicating no significant
change in DNA content of T. aestivum since its
origin.
4. There are variation in tetraploid wheat,
A: T. timopheevi has 95% DNA of T. turgidum
(Rees and Walters 1965).
B: Small differences between strains of T. turgidum
(Nishikawa et al 1978).
5. Interspecific variation occurs among putative genome
donors to polyploid wheat (Furuta et al 1986): Ae.
squarrosa (relative ratio;0.86) < Ae.
speltoides (0.92) < T. urartu (0.98) = T.
monococum (1.00) < Ae. bicornis (1.07) =
Ae. searsii (1.08) < Ae. longissima (1.21)
< Ae. sharonensis (1.27).
6. There is about twice variation in nuclear DNA content
among diploid species of wheat and Aegilops. Three
diploid species which are remotely related and whose species
are diagnostic to one another, Ae. squarrosa, Ae.
caudata and Ae. umbellulata belonging to the
lower DNA group and are known to be donors of the unaltered
or pivotal genomes to polyploid relatives as pointed out by
Zohary and Feldman (1962). On the other hand, the genomes (S
and M genome groups) of higher DNA group are modified in
ployploid species (Furuta 1975).
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