Rf8-Mediated T-urf13 Transcript Accumulation Coincides with a Pentatricopeptide Repeat Cluster on Maize Chromosome 2L

Abstract

Cytoplasmic male sterility (CMS) is a maternally inherited inability to produce functional pollen. In Texas (T)-cytoplasm maize ( L.), CMS results from the action of the URF13 mitochondrial pore-forming protein encoded by the unique T- mitochondrial gene. Full or partial restoration of fertility to T-cytoplasm maize is mediated by the nuclear gene in combination with one of three other genes: , , or *. encodes a mitochondrial aldehyde dehydrogenase whereas , , and * are associated with the accumulation of distinctive T- mitochondrial transcripts. -associated RNA processing activity was mapped to a 4.55-Mbp region on chromosome 2L that contains 10 pentatricopeptide repeat (PPR) encoding genes in the B73 5b.60 genome assembly. Genetic linkage analysis also indicated that * is positioned within this PPR cluster as well as , which restores USDA (S)-cytoplasm maize. Partially male-fertile plants segregated for the presence or absence of the -associated T- 1.42- and 0.42-kbp transcripts, indicating that the RNA processing event associated with these transcripts is not necessary for anther exsertion. In addition, a statistically significant delay in flowering was observed between partially male-fertile and mostly male-fertile plants. Taken together, these new results indicate that -mediated male fertility is under the control of more than one nuclear locus.