More than 1450 accessions of wild wheats were collected throughout their area of endemism in the Near East. Two types of diploids were distinguished by their seed protein electrophoretic pattern. One of these, Triticum boeoticum Boiss., was prevalent in all wild wheat areas. The other, occurring over the entire range of the tetraploids, was identified as T. urartu Tum., a species previously known only from Transcaucasia. The tetraploid T. diococcoides Körn. Schweinf. (AeAeBeBe), occupying the western arc of the Fertile Crescent, and T. araraticum Jakubz. (AtAtBtBt) occurring in the eastern arc and Transcaucasia, gave dissimilar but remarkably uniform albumin patterns from ethanol extracts of the seeds. A different combination of boeoticum and urartu biotypes accounted for all of the albumin bands in each of the tetraploid patterns obtained from water extracts. The morphological characters of the diploids were combined in the tetraploids. Hybrids between the wild diploid species were sterile, and showed 7 II at meiosis. The synthetic amphiploid from such a hybrid showed 10 II + 2 IV or 12 II + 1 IV. The triploid hybrid T. dicoccum × T. urartu showed 6-7 II. These observations implicate T. urartu as the missing B-genome donor to both of the tetraploids.

The diploid wheats Triticum boeoticum and T. urartu are sympatric with one another throughout the geographic range of the wild tetraploids. Reciprocal crosses between ecogeographic types within each diploid species gave viable seed, but interspecific crosses consistently gave viable seed only when T. boeoticum was the female parent. Apparently urartu cytoplasm in combination with the boeoticum genome resulted in nonviable seed. The endosperm failed to develop normally despite regular endosperm fertilization. The F1 plants obtained were completely self sterile although they showed regular intergenomic pairing (7II) at meiosis. Presumably the accumulation of cryptic differences between the two closely related genomes under reproductive isolation accounts for this sterility. The same accumulated cryptic differences could largely account for the preferential diploid pairing in the tetrapolid wheats which presumably were derived from such hybrids by chromosome doubling. The behavior of reciprocal crosses between the diploids and tetraploids suggested that T. boeoticum contributed the cytoplasm to both of the wild tetraploid species.

Protein spectra from 4n and 6n species of Triticum were obtained by electrophoresis of seed extracts on polyacrylamide gels. Homologies among the species with regard to protein bands were tested by comparing each species with the standard T. dicoccum in a protein mixture spectrum. By reference to two pairs of homologous bands, each spectrum was then adjusted to the migration velocity of the standard by photographic enlargement. The homologies were found to be consistent with evidence from conventional methods regarding genome relationships among the Triticum polyploids. T. dicoccoides and other known AABB tetraploids showed nine fast‐moving albumin homologues, while T. timopheevi and other known AAGG tetraploids showed seven. The two genomic groups had five albumin bands in common. The hexaploid (AABBDD) subspecies showed 12 albumin homologues, 9 of which were also homologous with the 9 of the AABB tetraploids and 3 of which were attributed to the D‐genome donor. Differences among species within each of the tetraploid genomic groups and among the hexaploid subspecies were largely confined to the slow‐moving bands of the gliadin series.

No abstract

Crude protein extracts were subjected to disk electrophoresis on polyacrylamide gel. The pattern obtained showed a fast and slow series of bands. In the fast series, the eight species of wheat of the Emmer group gave virtually identical eight-band patterns, and the four species of the Timopheevi group gave nearly identical six- or seven-band patterns. The groups consistently differed with respect to four bands. Two of these differences were attributable to the A genome.