| I. Research Notes Male fertility restoration against various alien cytoplasms. II. Genetical analysis of R-17127 D.K. GOTSOVA*, I. PANAYOTOV and K. GOTSOV Institute for Wheat and Sunflower, Tolbuhin, Bulgaria The male fertility restorer line R-17127 was produced in the Institute for Wheat and Sunflower, Tolbuhin, Bulgaria, by one of the authors (K. Gotsov). It had been selected from the cross MS (timopheevi)-Aurora x R-255-2 (USA) with Rf-genes originating from T. timopheevi. This line possesses the cytoplasm of T. timopheevi but is highly self-fertile and exhibits all the characteristics of a contemporary true-bred cultivar, namely, high yield potential, short stem, very strong resistance to stem, leaf and stripe rusts and strong resistance to powdery mildew. Its vegetative period is 3 to 4 days shorter than that of the Bulgarian standard Sadovo 1, while its grain shows very good qualitative indices, i.e. high 1000-kernel weight, gluten content up to 40% and excellent bread-making qualities. Our previous study (Panayotov et al. 1987) showed that line R-17127 restores high levels of male fertility in CMS-lines not only with the cytoplasm of T. timopheevi but also with the cytoplasms of T. dicoccoides var. spontaneovillosum, Ae. speltoides and Ae. triuncialis. Its ability to restore male fertility against T. timopheevi cytoplasm had been tested in the International Wheat Restorer Germplasm Screening Nursery (IWRGSN) in 1980 and proved to be both highly effective and very stable i.e., it occupied second place after R-line Zg 41 on the mean of eight trials in different countries. In the present study we attempted to determine the number of the Rf-gene(s) of R-17127 as well as their chromosomal location. Materials and Methods In order to determine the number of the male fertility restoring genes of R-17127 it was crossed as pollen parent to the male sterile (MS) lines of two common wheat cultivars, Aurora and Roussalka, with the cytoplasms of T. timopheevi, T. dicoccoides var. spontaneovillosum and Ae. speltoides. The F1 and F2 generations were grown in the field and 2 to 3 spikes per plant were bagged before anthesis. The selfed seed fertilities of the hybrids were determined as percentage of the seeds set in the 1st and 2nd florets of each spikelet. Simultaneously, monosomic analysis was carried out in order to determine the chromosomal location of the Rf-gene(s). First, at least three monosomic plants were identified from each line of the monosomic series of Chinese Spring (Sears 1954). They were pollinated by R-17127 and, after a standard chromosome checking procedure, the monosomic F1 plants were crossed as pollen parents to MS (timopheevi)-Siete Cerros 66 and the selfed seed fertilities of the hybrids were determined using 2-3 bagged spikes per plant. In the present study all plants were classified according to their self seed fertilities into two groups, fertile and sterile, the sterile group being comprised of the plants that did not set any seeds in the bagged spikes. |
| * Present address: Institute of Genetics, 1113 Sofia, Bulgaria |
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