Cytoplasmic reversion to fertility in cms-S maize need not involve loss of linear mitochondrial plasmids

Cytoplasmic male sterility of the S type (cms-S) in maize is characterized by the presence of two autonomously replicating plasmid-like elements, S1 and S2. These plasmids have not been found in the mitochondrial genomes of normal (male-fertile) maize nor previously in male-fertile cytoplasmic revertants. This paper reports the discovery of spontaneous cytoplasmic reversion to fertility in cms-S maize not involving the loss of S1 and S2 plasmids. Data are presented showing that loss of the plasmids during cytoplasmic reversion is under nuclear influence and is not a characteristic of the S cytoplasm itself.