Intracellular coevolution between nuclear and organellar genomes has
characterized the genetic makeup of all eukaryotes. In contrast to
most groups of organisms, plants are actively engaged in the
functional transfer of genes between organellar and nuclear genomes
and represent a model system for the study of the tempo, mode, and
consequences of gene transfer. Mitochondrial gene content in
angiosperms is highly irregular and nonrandom. Certain lineages appear
to have experienced recent bursts of gene loss and probable transfer
to the nucleus, but current taxonomic sampling is insufficient to
confirm this. We examine several of these potential cases of
accelerated gene loss through improved sampling. Mitochondrial gene
loss surveys are performed through a Southern hybridization approach
for as many species and genera within these lineages as are available.
Timing and patterns of gene losses are inferred from the best
available phylogenies. Groups in which losses are recent and transfer
to the nucleus is supported by other data are ideal systems for
examining underlying phenomena and characterizing intermediates in the
gene transfer process. We isolate nuclear encoded copies of
mitochondrial genes and examine evidence for functional, RNA-mediated
transfer, and successful retargeting to the mitochondrion.
Key words: gene transfer, genome evolution, mitochondrial genome