Conservative and Dynamic Evolution of Mitochondrial Genomes in Early Land Plants

Abstract

Early land plant mitochondrial genomes (chondromes) might have captured important changes of mitochondrial genome evolution when photosynthetic eukaryotes colonized land in a unprecedented scale, and thus deserve special attention in investigation of plant mito-chondrial genomes. The chondromes of land plants that are well adapted to the terrestrial environment, namely seed plants, show many derived characteristics, including large genome size variation, frequent occurrence of intra-genomic rearrangements, abundant introns and high levels of RNA editing. In contrast, the chondromes of charophytes, the closest algal relatives of land plants, are still largely ancestral in these aspects, resembling chondromes of early eukaryotes. Several recently sequenced chondromes from basal land plants including liverworts, mosses, hornworts and lycophytes have provided fresh insights into mitochon-drial genome evolution of early land plants. Comparative analyses of these genomes have identifi ed lycophytes, which represent the most ancient extant vascular plants, as the major 160 Yang Liu et al.