POLYMORPHISM AND CHROMOSOMAL LOCATION OF ENDOGENOUS ALPHA-AMYLASE INHIBITOR GENES IN COMMON WHEAT

Polymorphism of an endogenous alpha-amylase inhibitor in wheat was studied using isoelectric focusing followed by monoclonal antibody-based immunoblotting. Ten isoforms of the inhibitor detected in common wheat and its wild counterparts were assigned to five homoeologous loci. Three alpha-amylase inhibitor loci (Isa-1) were identified in common wheat and located on the long arms of chromosomes 2A, 2B and 2D. In a sample of 27 bread wheats, eight durum wheats, and 12 diploid wheat relatives, amphiploids and triticales, a high resolution isoelectric-focusing separation demonstrated two active and one null allele at the Isa-A1, two alleles at the Isa-B1, one allele at the Isa-D1, four alleles at the Isa-S1, and one allele at the Isa-G1 locus. The most frequent electrophoretic pattern of common wheat cultivars consisted of two isoforms, encoded respectively by the Isa-B1b, Isa-D1a alleles and the Isa-A1 null allele. All the durum wheats had only one inhibitor form controlled by allele Isa-B1b, which was accompanied by the null allele at the Isa-A1 locus.