Plant mitochondrial genomes and attempts to transform them

Abstract

Methods for stably transforming the mitochondrial genomes of multicellular organisms are presently unavailable.　Plant mitochondrial genomes encode genes not only for essential oxidative phosphorylation but also for agronomically important traits, such as cytoplasmic male sterility.　The lack of transformation methods prevents analysis of basic features of the genomes and their encoding genes, and prevents their application to agriculture.　Recently, a TALEN-based method was used to eliminate some mammalian mitochondrial disease genes.　Unlike mammalian mitochondrial genomes, plant mitochondrial genomes are large and vary in size.　They have many recombination-active repeats, and linear, branched and circular structures.　These complicated and dynamic structures make them difficult to stably transform, and this in turn makes it difficult to understand the molecular mechanisms underlying their complex structures.　This review describes the unusual features of plant mitochondrial genomes and recent attempts to transform the mitochondrial genomes of plants and other organisms.