Analysis of heteroplasmy in a cytoplasmic mutant of maize

The NCS6 mutant line of maize carries a deletion in the mitochondrial cytochrome oxidase subunit II (coxII) gene. The plant, characterized by a yellow striping of the leaves and reduced growth, is heteroplasmic. In order to analyze heteroplasmy in tissue cultures derived from NCS6 embryos the author has designed a set of three oligonucleotides that allow the amplification of sequences specific for the mutant and the normal mitochondrial genomes in a single polymerase chain reaction (PCR). Calli and suspension cells obtained from immature embryos show various degrees of heteroplasmy with a large predominance of the mutant genome. By analyzing DNA from single cells it was shown that heteroplasmic NCS6 plants and derived tissue cultures contain homoplasmic and heteroplasmic cells