Recombination of Mitochondrial Genes in Yeast

Mitochondrial mutations conferring resistance to specific antibiotics have been isolated in the yeast Saccharomyces cevevisiae. These mutations are located in the mitochondrial DNA (mtDNA) molecule (Nagley and Linnane, 1972; Faye et al., 1973; Deutsch et al., 1974). Mitochondrial recombination in yeast is interesting to consider in a symposium on mechanisms in recombination for several reasons: (1) mitochondrial genetics is a population genetics similar in certain aspects to bacteriophage genetics, (2) the elementary acts of recombination are of the nonreciprocal type, and (3) the occurrence of repetitive sequences in mtDNA of ρ- mutants offers a tool to study recombination in segments of repeated genes. Recently, extensive studies on multifactorial mitochondrial crosses have been published (Kleese et al., 1972; Suda and Uchida, 1972; Avner et al., 1973; Wolf et al., 1973; Howell et al., 1973; Rank, 1973 and Netter et al., 1974), using a standard cross procedure described by Coen et al. (1970), in which a random sample of a population issued from many zygotes after some 20 cell divisions is analyzed.