Mitochondrial plasmid-like DNAs of the B1 family in the genus Oryza: Sequence heterogeneity and evolution

Abstract

Four kinds of circular plasmid-like DNA, designated Bl, B2, B3 and B4, have been found in the mitochondria of Oryza sativa L. with an AA genome. Three novel Bl-homologous mitochondrial plasmid-like DNAs, designated, Ml, M2 and M3, were isolated in the present study from strains with CC and CCDD genomes in the genus Oryza. We cloned and sequenced these DNAs and found that the sequences of these molecules have wide regions of homology. Bl, M2 and M3 each lack about 300 bp of a region that is present in Ml and small repeats were found at the sites of deleted sequences. Therefore, we propose the hypothesis that the Bl family differentiated from a common ancient molecule that was similar to Ml via, probably, slipped mispairing during DNA replication at several stages in the evolution in the genus Oryza. © 1995, The Genetics Society of Japan. All rights reserved.