ISOZYME VARIATIONS IN AEGILOPS AND TRITICUM. I. ESTERASE ISOZYMES IN AEGILOPS STUDIED USING THE GEL ISOELECTROFOCUSING METHOD

Esterase isozymes in all Aegilops species were analyzed by the disc gel electrofocusing method using pH 5-8 carrier ampholite. Details of the procedure and the reliability of isozyme separation using this method were described.Esterase zymograms of individual strains were analyzed (Fig. 2), and an average zymogram of all species was obtained (Table 2). Zymogram complexity, given by summation of activity scores of all bands in the average zymogram, was compared among all species; Ae. columnaris showed the greatest while Ae. bicornis and Ae. biuncialis showed the least complexity. When compared among the three ploidy levels; di-, tetra-and hexaploid, no significant difference was found.Intraspecific variability of the zymogram was expressed as sum of two variances attributable, respectively, to differences among the strains and to the interaction between the strains and isozyme bands. Variability was low in diploid and high in tetraploid species. However, two exceptional diploids, both belonging to the Sitopsis section, showed high variabilities. Hexaploid species showed few variations.Similarity of zymograms between all species was examined using correlation coefficients obtained from their average zymograms. In diploids, some species showed high positive correlations, while others showed negative correlations. Their genome homology, expressed by chromosome pairing in the F1 hybrids, was not related to zymogram similarity, indicating that the isozyme pattern is controlled only by a few genes. Zymograms of tetraploid species showed high correlations to those of either diploid ancestor. The epistasis relationship among esterase genes in five genomes was postulated as follows: Cu=S>C=M>D. Hexaploid species showed a close relationship to the tetraploid but not to the diploid ancestors.