Deleterious mutations in a heterozygous chromosome result in recessive lethality in silkworm semiconsomic strains

Abstract

In this study, we found two embryonic lethal mutations,t04 lethal(l-t04) andm04 lethal(l-m04), in semiconsomic strains T04 and M04, respectively. In these semiconsomic strains, the entire diploid genome, except for one chromosome 4 of the wild silkwormBombyx mandarina, is substituted with chromosomes of the domesticated silkwormB. mori, andl-t04andl-m04mutations are located onB. mandarina-derived chromosome 4. The mutations responsible for thel-t04andl-m04were identified as theBombyxhomolog ofimaginal discs arrested(Bmida) andTATA Box Binding Protein-associated factor 5(BmTaf5), respectively. These findings indicate that both mutations were independently introduced during or after the development of semiconsomic strains. We conclude that the recessive embryonic lethality in the T04 and M04 strains is due to deleterious mutations produced in B. mandarina-derived chromosome 4.