in most organisms contain an essential but incomplete set of genes required
for their function (Christensen, 2013; Knoop, 2004; Schuster
and Brennicke, 1994). All known proteins required for plant mitochondrial
DNA (mtDNA) maintenance are encoded within the nuclear
genome of the cell. Many of these proteins are dual-targeted to both mitochondria
and plastids (Table 1; Christensen et al., 2005; Carrie et al.,
2009). However, replication of the mitochondrial DNA (mtDNA) is required
to provide templates for genes that must be expressed to maintain
optimal cellular metabolic functions.
Plant mitochondrial genomes on average are larger and exhibit a
higher level of complexity than those found in most metazoan mitochondrial
genomes. Regardless of these differences, the relative type