GENETIC STUDIES ON α-AMYLASE ISOZYMES IN WHEAT. III

INTRASPECIFIC VARIATION IN AEGILOPS SQUARROSA AND BIRTHPLACE OF HEXAPLOID WHEAT

Abstract

Fifty seven strains of KUSE (Kyoto University Scientific Expedition to The Karakoram and Hindukush) collection and three laboratory strains of Aegilops squarrosa were examined with respect to α-amylase isozymes of germinating seed. Seven zymogram patterns were identified, each of which consisted of a few isozyme bands most probably specified by the genes on chromosome 6D and only one by the gene on chromosome 7D. Among varieties of Ae. Squarrosa, var. typica was most variable, followed by var. strangulata. Variation in α-amylase isozymes, as in the other various characters, was most concentrated in the region of Gorgan, in decreasing order being the regions of Pahlavi, Tabriz and Tehran, and no variation in the other regions. From comparison of the zymograms between tetra- and hexaploid wheat, a particular zymogram pattern of α-amylase, Ams 3 was concluded as the one expected in the D genome donor to the main line of descent of hexaploid wheat. Ams 3 located most predominantly in the region of Gorgan, extending westwards along the south coast of Caspian sea up to Derbent, Caucasus. Therefore, it is most reasonable to consider that birthplace of hexaploid wheat should be extended to the south-east coast-land of Caspian sea from the area including south-west Caspian coast region and Transcaucasus, which the previous authors have indicated. On the other hand, discussion about independent origin of ssp. macha was made in view of the variant zymogram pattern.