| In the F2-F6 generations plants with ears differing
in form and color from the intermediate type occured at a high frequency.
Among these, no plants similar to hexaploid wheat type were found, not even
among the plants with lower chromosome numbers. Because of the presence
and high abundance of plants with 2n=49 chromosomes, it was necessary to
establish whether the reduction of chromosome number in the amphiploid is
the result of the loss of a whole genome or it is caused by random elimination
of single chromosomes. By the analysis of the marker chromosomes (Ae.
ovata: 1Cu(SAT), 2Cu(SAT), 7Cu and
7M0; T. turgidum ssp. carthlcium: 1B(SAT),
6B(SAT) etc) it was established that the reduction was caused
by random elimination of single chromosomes from both genomes (Fig.
1b). A similar phenomenon was observed in the course of the caryotype analysis of the 2n=56 plants occuring at a high frequency (66.9-62.5%) in the F6-F14 generations of the heptaploid (2n=70) of T. aestivum x T. timopheevi, as it was reported by us at the V. International Wheat Genetics Symposium in New Delhi (Fejer and Belea 1978). Unlike the amphiploids mentioned, the T. turgidum ssp. carthlicum x T. timopheevi octoploid (2n=56) was not reduced even in F5, an observation which is unambiguously verified by cytological analysis as well as by the esterase spectra obtained by IEFPA. Similarly, no reduction was observed in the F2-F4 generations of the hexaploid T. monococcum x T. timopheevi. The caryotype analysis of this hexaploid and of the parental plants as well as the PAGE esterase spectra support the assumption that the T. zhukovskyi species originates from T. momococcum and T. timopheevi by spontaneous amphiploidization. The so-called "fast moving" esterases of the amphiploid are identical with those of T. zhukovskyi obtained under the same conditions. Besides their theoretical importance, the amphiploids discussed are also of practical value. We succeeded in transferring the resistance of T. timopheevi against leaf and stem rust, powdery mildew etc. into common wheat by way of chromosome addition and in producing resistant lines from different combinations obtained by crossing the above mentioned amphiploids with common wheat varieties. Literature Cited BELEA, A. 1969. Genetic study on Triticum monococcum L. reduced from tetraploid to diploid. Acta Agronomica 18: 254-258 DAVIS, B.J. 1964. Disc Electrophoresis - II. Method and Application to Human Serum Proteins. Ann. N.Y. Acad. Sci. 121: 404-427 FEJER, O. and BELEA, A. 1978. Cytology and Isozymes of T. aestivum x T. timopheevi amphiploid. V. Intern. Wheat Genetics Symp. New Delhi. In press GORGIDZE, A.D. 1971. The synthesis of hexaploid wheats. Bull. Acad. Sci. Georgian SSR. 63: 669-672. GORGIDZE, A.D. 1973. The Basic Sources of the Origin and Formation of Initial Species of Cultural Wheat. Bull. Acad. Sci. Georgian SSR. 69: 425-428 HADLACZKY, Gy. and BELEA, A. 1975. C-banding in Wheat Evolutionary Cytogenetics. Plant Sci. Letters 4: 85-88 JOHNSON, B.L. 1975. Identification of the Apparent B-genome Donor of Wheat. Can. J. Genet. Cytol. 17: 21-39 MENABDE, V.L. 1971. A New View on the Phylogeny of the Genus Triticum L. Bull. Acad. Sci. Georgian SSR. 62: 413-416 PERCIVAL, J. 1921. The Wheat Plant. Duckworth Co. London, 473 SCANDALIOS, J.G. 1968. Genetic Control of Multiple Molecular Forms of Enzymes in Plants. A Review. Biochem. Genet. 3: 37-79 SCHRIMPF, K. 1951. Ein Beitrag zur Phylogenie und Systematik der Gattung Triticum. Z. Pflanzenzucht. 31: 42-71 |
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