| Cytology and isoenzymes of some Triticum auto-
and amphiploids O. FEJER and A. BELEA Institute of Genetics, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary. Introduction The autotetraploid and the two ssp. carthlicum amphiploids have been produced in our laboratory partly for theoretical, (mainly evolutionery), and partly for practical (disease-resistance etc.) purposes. The amphiploid T. monococcum L. x T. timopheevi Zhuk. we have obtained from the VIR (Leningrad). As a result of intensive research work, several theories have arisen on the origin and differentiation of wheats. For example, according to SCHRIMPF (1951), and later GORGIDZE (1973), MENABDE (1971) and JOHNSON (1975), the tetraploids have originated by autotetraploidization of diploid wheat species. PERCIVAL (1921), GORGIDZE (1971) and others proposed that the form range of the hexaploid wheat may have been enriched not only by the diploid Ageilops species, but also by the reduced forms of some tetraploid Aegilops (e.i. Ae. ovata, Ae. cylindrica). In this study we describe results obtained by cytogenetical methods (HADLACZKY and BELEA, 1975) and by the analysis of primary gene products, i.e. enzymes of the above mentioned auto- and amphiploids. Materials and Methods The autotetraploid T. monococcum was produced by a 0.02 per cent solution of colchicine. Amphiploids of ssp. carthlicum were obtained by treating the F1 hybrid grains with 0.05 per cent colchicine and 10 ppm giberellic acid. The enzyme extracts were obtained from the flour of mature whole grains by means of an MSE sonicator in 12.5 per cent sucrose solution. Isoelectric focusing on polyacrylamide gels (IEFPA) was performed according to Wrigley (1968, 1969), and polyacrylamide gel electrophoresis (PAGE) by the method of Davis (1964). Visualization of esterases was achieved using the method of Scandalios (1968), with minor modifications. Results and Discussion In spite of its 2n=28 chromosomes, the autotetraploid T. monococcum resembles morphologically the diploid T. monococcum rather than the tetraploid T. turgidum L. ssp. dicoccoides. The esterase zymograms of diploid and tetraploid T. monococcum are pratically identical. The comparison of the zymograms of the autotetraploid and of ssp. dicoccoides clearly shows that they are different, although the esterase bands characteristic of genome A are naturally present in ssp. dicoccoides too (Fig. 1a). In the majority of autotetraploid monococcum plants in F2 and mainly in F3, we observed the reduction of chromosome number to the diploid level, while the polyploid effect still persisted morphologically (BELEA 1969). These plant are characterised by the darker color of leaves as well as by the upright position of leaves and shorter and stronger straw. Later the morphological character of reduced plants became more and more different from that of the tetraploid plants and similar to the original diploid T. monococcum. The morphological and cytological characteristics of the octoploid (2n=56) F1 plants of the Ae. ovata x T. turgidum ssp. carthlicum amphiploid were intermediate. The isoesterase spectrum revealed by IEFPA also exhibits an additive effect, which is characteristic for the not reduced amphiploids. In later generations (F2-F6), however, a great reduction of chromosome number was observed (Table 1). Similarly, the fertility was found to decrease temporarily in the F2, and then to increase. However, the fertility in F5 was still lower than that in the first generation. This is known to be caused mainly by irregular chromosome pairing which results in sterility. |
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