The Effect of Gametogenesis Regimes on the Chloroplast Genetic System of Chlamydomonas Reinhardtii

In Chlamydomonas reinhardtii, gamete differentiation is induced by nitrogen deprivation. While cellular nitrogen content and amount of chloroplast DNA in cells of both mating types are reduced during gametogenesis, the spontaneous transmission of paternal (mt(-)) chloroplast alleles in crosses is specifically affected by the stringency of the nitrogen starvation regime used for pregrowth and gametogenesis of the mt(-) parent. In all cases, reciprocal crosses yielded biparental zygospores whose clones contain predominantly cells expressing only the chloroplast alleles from the maternal (mt(+)) parent. No differences attributable to strain divergence were seen in chloroplast gene inheritance pattern, DNA content, or the relative frequency of transmission of paternal chloroplast alleles to progeny of biparental zygospores.