| Genetic diversity of the cytoplasm among Triticum
and Aegilops Species having S and M group genomes, revealed by the
fertility spectrum Koichiro TSUNEWAKI Faculty of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606, Japan Cytoplasms of diploid species having the genomes of group S or M, and those of polyploid species which were assumed by Tsunewaki et al. (1980) to have received the cytoplasm from the donor of an S or M (or related) genome were transferred by repeated backcrosses from their carriers to 12 common wheats, i.e., T. aestivum var. erythrospermum (abbrev. Tve), strain P168 (P168), cv. Chinese Spring (CS), cv. Norin 26 (N26), strain Salmon (Slm), cv. Jones Fife (JF), cv. Selkirk (Sk) and cv. S-615 (S615), T. sphaerococcum (Sphr), T. compactum (Cmp), T. spelta (Splt) and T. macha (Mch). The 21 cytoplasms used were first introduced into common wheat at Kyoto University, Japan, North Dakota State University, USA (Dr. S.S. Maan), and the Institute for Wheat and Sunflower, Bulgaria (Dr. I. Panayotov), indicated by K, M and P, respectively. The fertility spectrum of these cytoplasms was examined against the 12 tester wheats, and the following results were obtained : The genetic diversity of the cytoplasm among diploid species having the S group genomes was great; the cytoplasms of Ae. speltoides-K, Ae. bicornis-M and Ae. longissima-P gave high fertility to all testers, while the cytoplasms of A. speltoides-M. Ae. aucheri-P and Ae. sharonensis-K caused complete or almost complete sterility in the testers at different combinations. The fertility spectrum of the first 3 species was essentially the same as that of Emmer (T. dicoccoides var. spontaneonigrum-K and T. dicoccum-K) and common wheats, which supports our previous proposal (Tsunewaki et al. 1980) that the cytoplasms of those polyploid wheats were derived from either Ae. speltoides, Ae. bicornis or Ae. longissima. The fertility spectra of the cytoplasms of Timopheevi wheats (T. dicoccoides var. nudiglumis-K, T. araraticum-M, T. timopheevi-K and T. zhukovskyi-M) closely resembled each other; the fertility spectrum of the Ae. aucheri-P cytoplasm was most similar to these spectra. These findings suggest that their cytoplasms originated from some form of diploid species having S genomes. The Ae. speltoides-M had an intermediate cytoplasm between the Ae. speltoides-K and Ae. aucheri-P cytoplasms, giving high fertility to 5 testers, Tve, P168, CS, Splt and Mch. Although no diploid species with the S group genomes had a cytoplasm identical to those of Ae. kotschyi-K and Ae. variabilis-K, the Ae. speltoides-K, Ae. bicornis-M and Ae. longissima-P cytoplasms were the same as those cytoplasms in their response to 9 of the 12 testers. Cytopalsms of Ae. comosa-K, Ae. heldreichii-P, Ae. uniaristata-M, and Ae. mutica-M and -P, all having the M group genomes were distinctly different with each other, although the Ae. heldreichii-P and Ae. mutica-P cytoplasms caused complete or almost complete sterility to all testers, and the Ae. uniaristata-M and Ae. mutica-M cytoplasms gave high fertility to 8 to 10 testers. None of them showed a fertility spectrum identical to that of the Ae. ovata-K cytoplasm. However, the Ae. mutica-P cytoplasm gave some fertility to P168. CS and Mch, all of which were fully fertile when the cytoplasm was introduced from Ae. ovata-K. Thus, the Ae. ovata-K cytoplasm seems to be somewhat related to the Ae. mutica-P cytoplasm. The present results on the fertility spectrum clearly demonstrate that; 1) great genetic diversity of the cytoplasm exists among diploid species having both the S and M group genomes, and 2) genetically similar cytoplasms to those of all polyploid wheats,Ae. kotschyi-Ae. variabilis complex, and Ae. ovata exist among these diploid species. (This study was supported in part by a Grant-in-Aid (No. 439016) from the Ministry of Education, Science and Culture, Japan) |