| Results and Discussion All, but one, F1's were sterile and there was no seed set in the selfed spikes. However, a positive relationship was observed between maintainer Mx 69, VAC (maintains the pollen sterility of the line M.S. 4692) and the male sterile line, M.S. 4696. The male sterile cytoplasm in both these A-lines was from T. timopheevi source (Table 1) and a particular B-line, Mx 69, VAC in this case, maintained pollen sterility of one A-line and restored completely fertility of another A-line. The finding of partly reciprocal restoration is new in wheat is quite new. However, in pearl millet, BURTON & ATHWAL (1968) reported two interacting cytoplasmic male sterility systems, in which maintainer of one sterility source restored fertility to the second source and vice-versa. In view of the present finding a thorough search may be made in wheat and its allied species for recovering a reciprocal restoration system. The three lines reported here to reveal maintainer-restorer interaction, can profitably be used in a three way cross hybrid programme. A possible explanation for such a maintainer-restorer mechanism could be that the restorer genes (R-genes) from T. timopheevi that have been transferred into wheat may not be allelic to sterility genes on the wheat chromosomes. It may be treated that the R-genes are additional material into the T. aestivum background. Restorer genes which are not allelic to sterility genes may co-exist in the same organism without covering the sterility genes. References BURTON, G.W. and ATHWAL, D.S. 1968, Reciprocal maintainer-restorer relationship between A1 and A2 sterile cytoplasms facilitates millet breeding. Crop Sci. 8: 623-634. JOPPA, L.R. and MCNEAL, F.M. 1969. Pollen fertilization by three spring wheats (Triticum aestivum, L.) of the male sterility induced by T. tmopheevi cytoplasm. Crop Sci. 9 : 239-240. MIRI, R.K., AMAWATE, J.S. and JAIN, H.K. 1970. N.P. 839, N.P. 883 and N.P. 880, new sources of fertility restoration in male sterile wheat. Wheat Inf. Serv. 31: 9-11. TAHIR, C.M. 1969. Sources of fertility restoring genes for Ae. ovata and T. timopheevi cytoplasms. Wheat Inf. Serv. 29: 15-17. |
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