| Source of fertility restoring genes for Ae. ovata
and T. timopheevi cytoplasms1)
Chaudhry M. TAHIR Laboratory of Genetics, Faculty of Agriculture, Kyoto University, Kyoto, Japan Hermaphroditic nature of wheat was reduced to unisex by the discovery of malesterility indacing cytoplasms (KIHARA 1953, FUKASAWA 1959, WILSON and Ross 1962 and MURAMATSU 1965), and later on clarification of mechanism of fertility-restoration as well as availability of some effective fertility restorers made the sublime objective of exploiting heterosis in wheat more distinct. But the problem of restoration even still exists; the restorers at hand are effective for certain varieties only, and there is also high degree of fluctuation in their effectiveness in different climatic zones. In this experiment 92 varieties or strains (73 T. aestivum, one T. compactum, one T. spelta, one T. vavilovii, four T. sphaerococcum and 12 synthesized 6x wheat strains) were crossed to completely male-sterile lines of common wheat possessing Ae. ovata or T. timopheevi cytoplasms, estimation of selfed seed fertility (%) in the F1 gave the account for the presence of fertility-restoring genes. Fertility-restorers for Ae. ovata cytoplasm: Selfed seed fertility of F1 hybrids between male sterile wheat and various pollen parents is given in Tables 1 and 2. Out of 73 T. aestivum varieties or strains tested for Ae. ovata cytoplasm, only nine strains, namely, P168 (93.3%), P169 (0.l%), P170 (67.5%), P171 (50.0%), P173 (44.0%), P174 (76.0%), BMUK nos. 3830 (2.2%), 3841 (0.3%), and 3844 (1.5%) restored male fertility in various degrees as shown in parentheses. Out of these, P168, P169, P170, P171, P173 and P174 are 6x derivatives from the cross between Ae. caudata and T. aestivum var. erythrospermum. P168 and P174 are known to carry a pair of a caudata chromosome C-sat-2, besides 20 pairs of wheat chromosomes (KIHARA 1959). All these derivative strains except P169 seem to have received restoring gene(s) from Ae. caudata, as T. aestivum var. erythrospermum with Ae. ovata cytoplasm is completely male sterile. None of the other species, i.e., T. compactum, T. spelta, T. sphaerococcum and T. vavilovii was found to possess dominant restoring genes, since all the F1 hybrids were completely sterile. |
| 1) This work has been supported by a Grant-in-aid from the Ministry of Agriculture, Japan. |
| --> Next |