Molecular Genetics of Mitochondrial Respiratory/ATP-Related Genes in Relation to Cytoplasmic Male-Sterility of Higher Plants

With the sequencing of the entire mitochondrial genome for some species, including Arabidopsis thaliana, Brassica napus, Beta vulgaris, Marchantia polymorpha, Oryza sativa, and Zea mays it is promising to explore the molecular genetics of mitochondrial respiratoryrelated genes in relation to some special traits with an emphasis on cytoplasmic male-sterility unique to plant mitochondria. Mitochondrial genomes encode only partial genetic information required for their biogenesis and function, however the vast majority is nuclear-derived, which is encoded by the nucleus and imported into mitochondria through the transported proteins. Consequently, most mitochondrial genetic and biochemical features displayed in plant mitochondria arise from the context of nuclear-mitochondrial co-evolution. Cytoplasmic male sterility (CMS), one useful trait for heterosis in agricultural production, is considered to be the result of the interactions between the mitochondrion and the nucleus in which the former exhibits the role of a tuning fork in nuclear gene expression that induces abnormal reproductive development. Likewise, expression of some mitochondrial genes is also regulated by nuclear genes in which the expression of some CMS-associated genes is influenced by nuclear restorer lines. In this review, we attempt to address the molecular genetics of mitochondrial respiratory/ATP-related genes concomitant with the occurrence of CMS. Furthermore, how the mitochondrion and nucleus interact on a molecular level to influence gene expression and function are also discussed in detail. _____________________________________________________________________________________________________________