Unique DNA associated with mitochondria in the “S”-type cytoplasm of male-sterile maize

Abstract
Mitochondrial DNA were prepared from maize [Zea mays] lines with normal cytoplasm and with the T, C, S and EP sources of male-sterile cytoplasms. Agarose gel electrophoresis of these preparations revealed a main high MW DNA band. The S cytoplasm was also characterized by the presence of 2 faster migrating DNA of MW 3.42 to 3.48 .times. 106 and 4.01 to 4.10 .times. 106. EM showed these unique DNA to be of different length, but their molecular configuration was not clearly established. It is possible that these unique DNA represent physical evidence of an episomal system previously postulated to function in the S male-sterile cytoplasm.