Cytoplasmic male sterility (CMS) is a common trait of plants characterized by an inability to produce functional pollen that is caused by the expression of poorly conserved mitochondrial genes. The effects
of CMS genes can be suppressed by the products of one or several nuclear genes termed restorer of fertility (Rf). In recent years, several Rf genes have been cloned from various plant species and most were shown to encode mitochondria-targeted pentatricopeptide repeat (PPR) protei ns. PPR proteins represent a large family of RNA-binding proteins of plants that is mainly known for their ability to facilitate expression of organellar mRNAs. Cloning of Rf-PPR genes thus revealed that PPR proteins can facilite but also block organellar RNA expression. Rf genes and their closely related homologues (called Rf-like genes) have specificities indicating that they follow an evolutionary dynamic that differs from that of other PPR genes. In my
presentation, I will show our latest results concerning the molecular characterization of a radish CMS fertility restorer, as well as some of our data concerning the analysis of the Rf-like subfamily in Arabidopsis.
These results will be discussed in light of cytonuclear co-adaptation in plants.