| Male Fertility Restoration: That the genome A of the diploid wheat has
a male fertility restoring chromosome (s) is indicated by the partial male
fertility of the trisomic plant No. 3095 (Table 2)
and by the segregation for male fertility restoration factor (s) in the
progeny from a cross (mst-Justin x T. boeoticum-type)
F1 x T. aestivum variety "Rescue". A partially male fertile
48 chromosome plant from this cross produced 2n=49 to 46 chromosome plants.
One of these with 2n=47 (21II+1III+2II,
18II+1IV+2III+1I) was highly
male fertile and gave good seed set on bagged heads. Others were either
partially fertile or completely male sterile. Conclusion: The authors concluded tentatively that substitution backcrossing of the common wheat variety "Justin" and T. durum into the cytoplasms of T. zhukovskyi and T. boeoticum-type diploid wheat, respectively, gives male sterile plants. Apparently male fertility restoring factors were present in some of the backcross plants. Reciprocal nuclear substitutions with T. timopheevi may be necessary to determine if the male sterility effects of these two cytoplasms are basically different from that of T. timopheevi. The occurance of a male sterility inducing cytoplasm at the three ploidy levels in Triticum may indicate that the cultivated tetraploid and hexaploid wheats were evolved after the migration of the A-genome to an alien cytoplasm of a genus (possibly Aegilops speltoides) that did not affect the male fertility of the new combinations. Literature Cited BOWDEN, W. M. 1959. The taxonomy and nomenclature of the wheats, barleys, and ryes and their wild relatives. Can. J. Bot. 37: 657-684. FUKASAWA, H. 1953. Studies on restoration and substitution of nucleus in Aegilotricum I. Appearance of male sterile durum in substitution crosses. Cytologia 18: 167-175. KIHARA, H. 1951. Substitution of nucleus and its effects on genome manifestations. Cytologia 16: 177-193. WILSON, J. A. and W. A. Ross 1962. Male-sterility interaction of the Triticum aestivum nucleus and Triticum timopheevi cytoplasm. Wheat Information Service No. 14. 29-30. (Received Sept. 20, 1966) |
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