Chloroplast segregation determined by mating type in Chlamydomonas

Reciprocal crosses Streptomycin- Streptomycin- resistant allele sensitive allele Chloroplast Nucleugy _\ type (4, X The cells of the two mating types fuse to form a diploid zygote. Nuclear fusion then occurs, but the chloroplasts inherited from the haploid parents remain separate. 2 ate yg The chloroplast inherited from the mtt parent is maintained. i The chloroplast inherited from the mt parent is . selectively degraded. Meiosis Meiosis g i E i i E iThe segregation of the mating type allele produces progeny i in a ratio of 2:2 as is typical for nuclear genes i w The ratio of chloroplast genotypes is 4:0 because all progeny L receive only the chloroplast contributed by the mt+ parent. J