Isozyme variations in Aegilops and Triticum. IV. The origin of the common wheats revealed from the study on esterase isozymes in synthesized hexaploid wheats.

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Abstract
Esterase isozymes in 2 kinds of synthesized hexaploid wheat and its parental strains were analyzed by the isoelectric focusing method using pH 6-8 carrier ampholite. In present-day hexaploid wheat, 3 similar patterns of esterase isozymes were found. A large number had 9 esterase bands, which are controlled by the genes on homeologous chromosomes 3. On the other hand, the parental species of the hexaploid also showed inter- as well as intraspecific variations. Seven different zymograms were observed in the tetraploid wheats, among which type 4 distributed most widely in tetraploid species. Moreover, most bands of this zymogram were commonly found in the zymograms of common wheat. Therefore, the donor of AB genome to common wheat seems to have had this zymogram. The Tetra-Canthatch (AABB) which the D genome was removed from Canthatch (AABBDD) had the same zymogram, the type 4, of present-day tetraploid species. The type 4 of the esterase zymogram was, also, posturated as AB genome donor from this evidence. Another parent, A. squarrosa, involved 3 types of zymograms. Artificially synthesized hexaploid wheat as the hybrids between type 4 tetraploid and 3 types of A. squarrosa were produced. Combinations between type 4 tetraploid and type 2 A. squarrosa showed the same zymogram as compared with present-day hexaploid wheat. Therefore, type 2 A. squarrosa was expected as D genome donor. Concerning the geographical distribution of type 2 A. squarrosa, this type was found in the Elbruz Mountains along the coast of the Caspian Sea and Transcaucasus [Europe]. Yet type 2 was not found in Pakistan or Afghanistan. The birthplace of hexaploid wheat is probably the region from the southwest Caspian belt to Transcaucasus.