Structural and Functional Organization of Genes That Induce and Suppress Cytoplasmic Male Sterility in Plants

Cytoplasmic male sterility (CMS) is peculiar to all higher plants; it occurs in natural populations or arises under distant (sexual or somatic) hybridization. CMS and fertility restoration are important speciation characters and also the most valuable for breeding. The main features of structural and functional organization of CMS-associated mitochondrial genes in forms with different sterilizing cytoplasms are considered. The origin of nuclear PPR genes as the most probable candidates associated with pollen fertility restoration trait is discussed; examples of “atypical” Rf genes of some species are given. On the basis of data on studies of diverse CMS- Rf genetic systems, the possibility of parallelism in the variability pattern of genes responsible for sterility and male fertility restoration in plants is shown.