Mating Type Determination of Chlamydomonas reinhardtii by PCR

We describe a quick and reliable protocol to determine the plus or minus mating type of haploid Chlamydomonas reinhardtii strains from very small amounts of cells. The method combines a fast DNA preparation adapted from forensic work of Walsh et al. (1991) with one for use with Chlamydomonas by Berthold et al. (1993). We used PCR to amplify the minus-specific mid gene (minus dominance) or the plus specific fus1 gene (fusion). Both primer pairs have the same optimum annealing temperature and could be used in the same PCR reaction. The fus1 and mid amplification products could be distinguished by agarose gel electrophoresis due to their different PCR product size. Diploid strains, which should have both mating type genes, could also be detected by the occurrence of both amplification products.