| As evident from Table 1, when theoretical ratios
were compared with observed results, the data in 1D and 3D gave a good fit
to 12 : 25 : 4 ratio and the remaining lines gave a good fit to 25 : 4 ratio.
In a reciprocal cross where F1 plants were used as female parent,
all the four types of gametes were transmitted in the expected proportions.
It was therefore concluded that rye chromosome I was genetically related
to both 1D and 3D. That such a relationship was possible, is evident from
the fact that JENKINS (1966) was able to substitute rye chromosome I for
all wheat chromosomes of the homoeologous groups 1 and 3. There is increasing
evidence that these substitution lines are fertile and meiotically stable.
If Secale cereale was derived from the same diploid ancestor which gave rise to the three diploid progenitors of wheat, normally we would expect homoeologous relationship of a rye chromosome with chromosomes of only one homoeologous group in wheat. But as pointed out by RILEY & KIMBER (1966) S. cereale has at least two translocations and this species was derived from S. montanum. Therefore rye chromosome I in the present study is presumably the result of such a translocation, thus having segments from two original chromosomes. It is natural therefore to expect that a more precise relationship can be obtained only by using S. montanum. It is unfortunate that in most of the wheat improvement programmes in the past, S. cereale has been used. It is only now that S.montanum is being used at certain places. Literature BAKSHI, J.M. & A.M. SCHLEHUBER 1959. Proc. Okla. Acad. Sci. 39 : 16-21. BHATTACHARYYA, N.K. & B.C. JENKINS 1960. Can. J. Genet. Cytol. 2 : 268-277. HACKER, J.B. 1965. Can. J. Genet. Cytol. 7 : 316-327. JENKINS, B.C. 1966, Proc, 2nd Int, Wheat Genet, Symp. Lund. 301-321. JOHNSON, R. 1966. Can. J. Genet. Cytol. 8 : 279:-292. KNOTT, D.R. 1964. Can. J. Genet. Cytol. 4 : 500-507. O'MARA, J.G. 1947. Genetics. 32 : 99-100. RILEY, R. 1964. Proc. 11th Int. Cong. Genet., The Hague 3 : 681-688. RILEY, R., V. CHAPMAN and R.C.F. MACER l966 Can.J. Genet. Cytol. 8 : 616-630. RILEY, R. and G. KIMBER 1966. Rep. Pl. Breed. Inst. Cambridge. 6-36. SEARS, E.R. 1966. Chromosome Manipulations and Plant Genetics. 29-45. WEINHUES, A.1960. "Vortrage fur Pflanzenzuchter" D.L.G. Verlag. Frankfurt. (Received January 6, 1968) |
| <-- Back |