MATERNAL INHERITANCE OF THE CHLOROPLAST AND MITOCHONDRIAL GENOMES IN CHEILANTHOID FERNS

Molecular data from the chloroplast genome are being used to reconstruct the phylogeny and revise the problematic taxonomy of the xerically adapted cheilanthoid ferns. Chloroplast DNA based phylogenies trace maternal, paternal, or biparental lineages, depending on the mode of inheritance of the chloroplast genome, and instances of all three modes of inheritance are known in the seed plants. Evidence for biparental and uniparental inheritance in ferns has been presented, but the distinction between maternal and paternal uniparental inheritance has not been rigorously made, and the mode of inheritance in cheilanthoid ferns is completely unknown. Based on a natural hybrid population in the cheilanthoid genus Pellaea in which the maternal and paternal derivations of the hybrid are unambiguously known, restriction fragment length polymorphisms of chloroplast DNA demonstrated simple maternal inheritance of the chloroplast genome. This hybrid complex was also examined for restriction fragment length polymorphisms of its mitochondrial DNA, providing the first direct evidence that the mitochondrial genome in ferns is maternally inherited.