CMS
Delph LF, Touzet P & Bailey MF 2007 Merging theory and mechanism in studies of gynodioecy. TREE 22:17-24.
- CMS is caused by chimeric genes, formed from segments of other mitochondrial genes as well as from segments of unknown origin
- these segments form open reading frames(ORFs) that are transcribed and translated to produce a novel protein
- they are commonly co-transcribed with other mitochondrial genes
- this co-transcription is one factor that could cause negative pleiotropic effects of nuclear restorer alleles
- most evidence is consistent with an active role for the new allele and its products, including several cases in which the new protein appears to act as a toxin that interferes with mitochondrial respiration
- recent evidence in petunia, radish and rice suggests that restorer genes have been recruited from the pentatricopeptide (35 amino-acid) repeat gene family (PPR) gene family, which is involved in organelle gene expression
- just like the CMS genes that they restore, the various nuclear restorer alleles reviewed here differ markedly from each other
- with the exception that all are likely to lower pollen production and/or viability as a component of their cost relative to wild-type alleles
- some nuclear restorers appear to occur at novel loci
- whereas others are likely to have been recruited from a locus that was already involved in the regulation of mitochondrial gene expression
