| Gene flow between any F1 amphidiploids comprising any other
Aegilops or Triticum species proposed as B genome donors and
T. monococcum and the present day tetraploid wheat does not appear
to be likely as shown for amphidiploids involving Ae. speltoides
and Ae. bicornis (SEARS 1956) for Ae. longissma (TANAKA 1956,
FELDMAN 1978) and T. urartu (DHALIWAL & JOHNSON 1982). TANAKA
et al. (1978) showed that only after successive growing of the amphidiploid
Ae. speltoides x T. monococcum from the F1 to the
F11 generation, the hybrid between the progressive generation
and T. turgidum dicocoum yielded 2 F2 viable seed. The
F2 plants were found to have only a low frequency of bivalents
(mean of 6.96 per cell) and relatively high frequency of univalents and
multivalents leading to poor seed fertility of only 4.1%. The possibility
of gene flow between the F1 amphidiploid (Ae. sharonensis
x T. monococcum) and the T. turgidum dicoccoides found in
the present study in addition to the chromosome stability of this amphidploid
and its high fertility and high prominents combining ability with dicocooides
(small grassy type) (KUSHNIR & HALLORAN 1982a, 1982b) serves as further
support for Ae. sharonensis as the putative donor of the B genome
of wheat. Literature Cited CHAPMAN. V., MILLER, T.E. and RILEY, R. 1976. Equivalence of the A genome of bread wheat and that of Triticum urartu. Genet. Res. Camb. 27: 69-76. DHALIWAL, H.S. and JOHNSON, B.L. 1982. Diploidization and chromosomal pairing aiffnities in the tetraploid wheats and their putative amphiploid progenitor. Theo. Appl. Genet. (In Press). DVORAK, J. 1976. The relationship between the genome of Triticum urartu and the A and B genomes of Triticum aestivum. Can. J. Genet. Cytol. 18: 371-377. FELDMAN, M. 1978. New evidence on the origin of the B-genome of wheat. Proc. 5th Int. Wheat Genet. Symp. New Delhi, Indra, pp. 120-l32. KUSHNIR, U, and HALLORAN, G.M. 1982a. Evidence of Aegilops sharonensis Eig as the donor of the B genome of wheat. Genetics. 99: 495-512. KUSHNIR, U, and HALLORAN, G.M. 1982b. Quantitative studies of the amphidiploid (Aegilops sharonensis x Triticum monococcum) and the origin of the B genome of wheat. Wheat Inf. Serv. 54: 12-16. SEARS, E.R. 1956. The B genome of Triticum. Wheat Inform. Serv. 4: 8-10. SEARS, E.R. 1981. Transfer of alien genetic material to wheat in Wheat Science Today and Tomorrow. Ed. Evans, L.T., and Peacock, W.J., Cambridge University Press, pp. 75-89. TANAKA, M. 1956. Chromosome pairing and fertility in the hybrid between the new amphidiploid S1 S1-AA and emmer wheat. Wheat Inform. Serv. 3: 21-22. TANAKA, M., KAWAHARA, T. and SANO, J. 1978. The origin and the evolution of wild tetraploid wheats. Wheat Inform. Serv. 47: 7-11. |
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