High heterozygosity at Gpi-1 in gynogenetic diploids and triploids of ayu Plecoglossus altivelis.

Abstract

Gynogenetic diploids and triploids of ayu, Plecoglossus altivelis were induced by retaining the second polar body of the fertilized egg by cold shock using parents of 24 males and 12 females. The Gpi-1 isozyme locus was detected for the control diploid, gynogenetic diploid, and triploid populations. The heterozygous triploids, which are specified in density distribution of three bands were easily distinguished from the heterozygous diploids control. The recombination rate between Gpi-1 and centromere was estimated as 100% based on the percentages of recombinants and non-recombinants derived from one parent which was rare genotype Gpi-1(A/C). The heterogygosity was very high at Gpi-1 locus;0.490 in control diploid population, 0.517 in gynogenetic diploid population, and 0.800 in triploid population. The observed values of heterorygosity well accorded with those expected by the allelic frequencies in parents used here. The meaning of recombination was discussed from the view points of breeding science.