Molecular heterogeneity in mitochondrial and chloroplast DNAs from normal and male sterile cytoplasms in sugar beets.

Mitochondrial (mt) and chloroplast (ct) DNAs were prepared from normal (N) and male sterile (S) cytoplasmic lines of sugar beet. The DNAs were cleaved with BamHI, EcoRI, HindIII and SalI enzymes, and the resultant fragments were fractionated by agarose gel electrophoresis. The results showed that N and S cytoplasms contained distinct mtDNA. Although most of the DNA fragments were common to these two cytoplasms, each cytoplasm was readily characterized by bands specific to that cytoplasm. In addition, these distinctive cleavage patterns were invariant in different nuclear backgrounds. In contrast to the marked variation in mtDNA, restriction fragment analyses of ctDNA demonstrated little difference between both cytoplasms. Only HindIII digestion showed one band missing in the S genome. The data presented here provides circumstantial evidence for mitochondrial involvement in the inheritance of cytoplasmic male sterility in sugar beet.