| It should be noted that among the chromosomes from the alien species,
whose homoeologous relationships are known, none has so far been assigned
to the homoeologous group 4. If this observation is considered in the light
of the variability for alkaline phosphatase and alcohol dehydrogenase in
the wheat chromosomes of the homoelogous group 4, we may expect that the
chromosomes from homoelogous group 4 in the Triticinae have perhaps differentiated
to a higher degree than the chromosomes of other homoeologous groups. It
is also possible, therefore, that no disomic alien substitution may be obtained
for any of the wheat chromosomes belonging to this group, because the differentiation
of high degree would not allow compensation possible. However, JENKINS (1966)
reported the substitutions of rye chromosome V for 4B and 4D, although the
correctness of wheat chromosomes was not checked. GUPTA (1971) pointed out
that rye chromosome V (designated after JENKINS 1966) did not show any compensation
for any chromosome of the D genome in the pollen. He also indicated that
this rye chromosome may be 4R, which lost much of its homoeology. However,
using amphiploids, alien addition lines and the six nullisomic-tetrasomic
lines belonging to the group 4, it should be possible to find out which
chromosome in an alien species is having genes for alkaline phosphatase
and alcohol dehydrogenase. In the absence of sustitution lines this technique
may give valuable information regarding the relationship of a chromosome,
which has lost most of its similarity due to differentiation. Alien chromosomes
belonging to homoeologous group 4 can thus be identified. Rye chromosome
V referred above may be particularly tested for the presence of the genes
for alkaline phosphatase and alchool dehydrogenase. This would confirm whether
this chromosome is really 4R. We would have liked to undertake such a project
ourselves, but for the lack of facilities in this laboratory. It is hoped,
therefore, that such a project will be undertaken elsewhere. Literature cited BAKSHI, I. S. and A. M. SCHLEHUBER 1959. Oklahoma Acad. Sci. Proc. 39: 16-21. BARBER, H. N. 1969 TAXON 19: 154-160. BELFIELD, A. M. and R. RILEY 1969. "Chromosome Today Volume Two" (Eds. DARLINGTON, C. D. and K. R. LEWIS) pp 5-11. BREWER, G. J., C. F. SING and E. R. SEARS 1969. Proc. Natl. Acad. Sci, U.S.A. 64: 1224-1229. CHAPMAN, V. and R. RILEY 1970. Nature 226: 376-377. GUPTA, P. K. 1971. Genetica 42 (2): (in press) HART, G. E. 1970. Proc Natl. Acad. Sci., U.S.A. 66: 1136-1141. JENKINS, B. C. 1966. Proc. 2nd Intern. Wheat Genet. Symp. 301-312. JOHNSON, R. 1966. Can. J. Genet. Cytol. 8: 279-292. QUINN, C. J. and C. J. DRISCOLL. 1967. Crop. Sci. 7: 74-75. RILEY, R., V. CHAPMAN and R. C. F. MACER 1966. Can. J. Genet. Cytol. 8: 616-630. SEARS, E. R. 1966. In "Chromosome manipulations and Plant Genetics" (Eds. RILEY, R. and K. R. LEWIS) pp. 29-45. (Received March 13, 1971) |
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