Genetic control of bluish shell color variation in the Pacificabalone, Haliotis discus hannai

摘要

Shell color variation is one of the more interesting phenomena in abalone breeding. Especially, the identification of inheritable shell color will be a useful visual genetic marker. Bluish shell colored individuals were discovered in one full-sib family A out of nine families (A to I) in the Pacific abalone, Haliotis discus hannai. The segregation of the variant (bluish) type and the normal (greenish) type was 13:27, suggesting the existence of a recessive allele at a single locus. To clarify the genetic control of shell color variation, mating experiments were designed for the F2 generation among the bluish-type and greenish-type individuals within the full-sib family A. All individuals were of the greenish type in the three full-sib families between greenish-type female and greenish-type male, whereas all individuals were of the bluish type in the six full-sib families between bluish-type female and bluish-type male. All individuals were of the greenish type in the four full-sib families between bluish-type female and greenish-type male, whereas segregation of the greenish type and the bluish type was observed in the two full-sib families between greenish-type females and bluish-type males. The observed numbers showed no significant deviation from expected numbers calculated under Mendelian segregation (1:1) in each family. These results indicate that the bluish and greenish shell color variant types are controlled by a recessive allele (b) and a dominant allele (G) at a single locus. Therefore, the genotype of parental individuals (f1 and m1) of the full-sib family A is estimated as G/b. To elucidate the genetic control of shell color variation, further mating experiments were designed for the F2 generation within and between full-sib families D and G in which the male parent (m1) is common with the family A. As expected, segregation of the bluish and greenish types was observed in the two full-sib families out of 13 families. The observed numbers showed no significant deviation from expected numbers calculated under Mendelian segregation (3:1). These results support the elucidation of the genetic control of shell color variations described in the present study.