Transmission and recombination of chloroplast genes in asexual crosses of Chlamydomonas reinhardtii. II. Comparisons with observations of sexual diploids.

Patterns of biparental chloroplast gene transmission in Chlamydomonas reinhardtii diploids produced by polyethylene glycol (PEG) fusion were found to be similar to those seen in sexual diploids (VanWinkle-Swift and Birky 1978). Examination of the phenotypes of diploid clones showed that the PEG diploids produced a heterogeneous set of allelic frequencies. Neither the frequencies of parental nor recombinant phenotypes were normally distributed. In addition, frequencies of reciprocal recombinant phenotypes showed no significant correlation in the clones from individual PEG diploids. The frequencies of parental phenotypes, on the other hand, were significantly negatively correlated. Like the data from sexual diploids, this is evidence that recombinant frequencies from clones of PEG diploids are not directly related to frequencies of reciprocal recombination. The similarity of results obtained in sexual and PEG diploids supports the hypothesis that the mechanisms operating during biparental chloroplast gene inheritance in PEG diploids are identical to those in sexual diploids.