Variation, geographical distribution and genetical analysis of esterase isozymes in foxtail millet, Setaria italica (L.) P. Beauv.

The esterase isozymes of 432 strains of foxtail millet, Setaria italica (L.) P. Beauv., collected from different areas throughout Eurasia, were investigated by gel isoelectric focusing. Five phenotypes were recognized, based on the combination of five major activity bands. Cross experiments among different phenotypes revealed these isozymes to be controlled by two codominant alleles and a null allele on the locus, Est-1, and three codominant alleles on another independent locus, Est-2. On locus Est-1, 388 strains had Est-1 (a), 41 had Est-1 (b) and three had Est-1 (null) alleles. Est-1 (a) was widely distributed throughout Eurasia, while the distribution of Est-1 (b) and Est-1 (null) was distinctly restricted. On locus Est-2, 417 strains had Est-2 (a), nine had Est-2 (b) and six had Est-2 (c) alleles. Est-2 (a) was widely distributed throughout Asia to Czechoslovakia, but was not detected in the western part of Europe. Est-2 (b) was found in all of the strains from the western part of Europe and in one of the Indian strains. Est-2 (c) was rarely found in Japan and China. The distribution of Est-2 (a) and -2 (b) might indicate some degree of phylogenetic differentiation between the Asian and the European strains. Polymorphism in both loci was observed only in Chinese strains.