| Male sterility interaction of the Triticum aestivum
nucleus and Triticum timopheevi cytoplasm1 J. A. WILSON2 and W.M. Ross Ft. Hays Branch, Kansas Agricultural Experiment Station and Crops Research Division, ARS, USDA, Hays, Kansas, U. S. A. Cytoplasmic male sterility in backcross derivatives of common wheat having Aegilops caudata L. and Aegilops ovata L. cytoplasm has stimulated interest in other species of Hordeae. Work has been done along this line involving various species. Kihara3 indicated that substituting Triticum dicoccum Schrank. nucleus into T. timopheevi Zhukov. cytoplasm resulted in male and female fertility. We used T. timopheevi as the female parent in greenhouse crosses to T. aestivum L., 'Bison', C. I. 12518. Bison was used recurrently as the male parent in subsequent backcrosses. Slight pollen fertility was expressed in the F1, T. timopheevi x Bison, and BC1, T. timopheevi x Bison2. Of five BC1 plants, one showing partial pollen fertility was used as the female in the second backcross. All 10 BC2 plants, T. timopheevi x Bison3 were pollen sterile. One of the pollen sterile BC2 plants looked quite like the recurrent parent, Bison. Six of the 10 BC2 plants were backcrossed again to Bison. From these backcrosses, six BC3 families, T. timopheevi x Bison4, consisting of 20 plants were grown out. All 20 plants were male sterile. At least two families in the BC3 were meiotically unstable. Chromosome observa tions on a family that appeared Bison-1ike indicated that they were stable meiotically and at the hexaploid chromosome number level. In the BC4, T. timopheevi x Bison5, 17 of 19 plants in five families again were pollen sterile. The two plants shedding pollen came from the family of greatest meiotic instability in the BC3 but doubtfully were segregates carrying pollen-restoring genes from T. timopheevi. More likely they were rogues coming from a mechanical mixture. Male sterility in the hexaploid lines was characterized by shriveled and curved anthers with aborted pollen. The appearance of the antenrs was very similar to those observed in male-sterile varieties with Ae. ovata cytoplasm. Seed was obtained easily on these lines during backcrossing. |
| 1 Contribution No. 168, Ft. Hays Branch Station. 2 Now Wheat Research leader, Dekalb Agricultural Association; lubbock, Texas. 3 Kihara, H. Fertility and morphological variation in the substitution and restoration backcrosses of the hybrids, Triticun vulgare x Aegilops caudata. In Proc. 10th Int. Cong. Gen. 1958. University of Toronto Press. Toronto, Canada. p. 166. 1959. |