Gliadins and high-molecular-weight glutenin subunits variation in Aegilops searsii.

The chromosomal location of genes encoding storage proteins in cultivated polyploid wheats is well established. Gliadins and high-molecular-weight (HMW) glutenin subunits are encoded by complex loci located on the short arms of homoeologous groups 1 and 6 and on the long arm of homoeologous group 1, respectively (Payne, 1987). The chromosomal control of endosperm proteins has been ·studied in various species of the tribe of Triticeae to assess whether or not the genes controlling seed storage proteins in other genomes have a similar chromosomal distribution to wheat and to establish the homeological relationships. Establishing these relationships is of extreme importance in wheat breeding programmes when alien genetic material has to be transferred in interspecific crosses. Aegilops searsii is a diploid (2n = 14, genome SsSs, autogamous annual grass of the Sitopsis section of the genus Aegilops native to eastem Mediterranean regions and central Asia (Feldman and Kislev, 1977) and, according to Feldman ( 1978), it could be considered as the B genome donor to cultivated wheats. Many researchers, on the basis of results of various studies, support this hypothesis, including Kerby and Kuspira, 1987. Seed storage proteins have been suggested as a possible tool in wheat evolutionary studies (Lafiandra et al., 1989), and Konarev ( 1983) and Cole et al. ( 1981 ), using seed storage proteins, have indicated that both Ae. longissima and Ae. searsii are possible donors of the B genome to cultivated polyploid wheats. The production of Chinese Spring-Ae. searsii disomic addition lines (Pietro et al., 1983) makes it possible in this species to allocate gliadin and glutenin genes to specific chromosomes. This, along with the study of protein variation, might help in establishing phyletic relationships with cultivated wheats.