Alpha-Amylase Genes in Wheat

The various forms of the enzyme are, of course, products of several structural genes, and genetic analysis can reveal additional information concerning the relationships between the various isozymes. The initial identification of the chromosomal locations of the a-amylase structural genes was made by K. Nishikawa and M. Nobuhara. The most common method of ascertaining the chromosomal locations of enzyme structural genes in wheat is nullisomic analysis, usually by use of the Chinese Spring nullisomic-tetrasomic and ditelocentric stocks developed by E. R. Sears at Columbia, Missouri. The isozymes with more basic basic isoelectric points are all encoded by the a-Amy-1 genes on the long arms of the group 6 chromosomes. The individual a-Amy-1 and a-Amy-2 loci probably comprise tightly linked complexes of ‘genes’ coding for several individual isozymes, and may be the products of successive evolutionary duplication and mutation. Observation of a range of varieties reveals considerable variation in isozyme patterns.