LINKAGE OF A KNOWN CHLOROPLAST GENE MUTATION TO THE UNIPARENTAL GENOME OF CHLAMYDOMONAS REINHARDII

Laurens J. Mets ¹ and Lois J. Geist ²

¹ Department of Biology, University of Chicago, Chicago, Illinois 60637
² School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106

Data are presented that associate three new markers with the uniparental linkage group in Chlamydomonas reinhardii. One of these, mutant 10-6C, is a genetic marker for the structural gene of the large subunit of ribulose bisphosphate carboxylase. These results provide the first direct link between the uniparental gene map and the physical map of chloroplast DNA. The other two markers, Dr2 (DCMU resistant) and 8-36C (deficient in photosystem II activity), map to a single locus. The data suggest that mixing in zygotic chloroplasts may not be complete so that input genomes do not have equal opportunities to recombine. The data are not compatible with simple linear or circular maps but can be explained on the basis of the known physical structure of chloroplast DNA.