Monokaryotic chloroplast mutation has no effect on non-Mendelian transmission of chloroplast and mitochondrial DNA in Chlamydomonas species.

We studied whether the monokaryotic chloroplast (moc) mutation affects the transmission of chloroplast and mitochondrial DNA in Chlamydomonas species. We used a previously isolated moc mutant from our cell line G33, which had only one large chloroplast nucleus. To obtain zygotes, we crossed the mutant cells with wild-type cells, and mutant cells with receptive mates (females [mt+] with males [mt-]). In these zygotes, we recorded preferential dissolution of mt- parental chloroplast nuclei and fusion of the two cell nuclei. Antibiotic-resistance markers of chloroplast DNA were maternally transmitted in all crosses. PCR analysis of the cytochrome b (cob) gene sequence showed that the mitochondrial DNA was paternally transmitted to offspring. These results suggest that the moc mutation did not affect the organelle DNA transmission.