Genetics of Body Color Inheritance in Thai and Egyptian Red Tilapia Strains

Abstract

The Mendelian mode of red bcx:ly color inheritance in Thai and Egyptian strains of red tilapia was studied. Breeding between red x red and red x wild parents resulted in mostly all red progenies; and in some red x wild crosses, progenies were also segregated into red and wild types. The FI red hybrids mated inter se and back-crossed to wild type, the progeny phenotype segre­gated closely into approximating the expected 3 red: 1 wild type and 1 red: I wild type ratios, re­spectively. These results demonstrate that red body color in the two mutant strains of tilapia is controlled by a single autosomaJ dominant "R" gene. But the red strains contain different propor­tions of heterozygotes (Rr). In order to produce pure breeding strains, it is important to identify heterozygotes so the "r" aJlele can be selected out. In light of the present study, the progeny test­ing technique has been proposed as a probable solution.