Rf8-Mediated T-urf13 Transcript Accumulation Coincides with a Pentatricopeptide Repeat Cluster on Maize Chromosome 2L
- Julie Meyer,
- Deqing Pei and
- Roger P. Wise
- J. Meyer, D. Pei, and R.P. Wise, Interdepartmental Genetics Program, Iowa State Univ., Ames, IA 50011; and Department of Plant Pathology and Microbiology, Iowa State Univ., Ames, IA 50011; J. Meyer, present address: Regulatory Sciences Product Characterization Center, Monsanto, St. Louis, MO 63167; D. Pei, present address: Dep. of Biostatistics, St. Jude's Children Research Hospital, Memphis, TN 38105; R.P. Wise, USDA-ARS, Crop and Insect Genetics, Genomics, and Informatics Research Unit, Iowa State Univ., Ames, IA 50011
Cytoplasmic male sterility (CMS) is a maternally inherited inability to produce functional pollen. In Texas (T)-cytoplasm maize (Zea mays L.), CMS results from the action of the URF13 mitochondrial pore-forming protein encoded by the unique T-urf13 mitochondrial gene. Full or partial restoration of fertility to T-cytoplasm maize is mediated by the Rf2a nuclear gene in combination with one of three other genes: Rf1, Rf8, or Rf*. Rf2a encodes a mitochondrial aldehyde dehydrogenase whereas Rf1, Rf8, and Rf* are associated with the accumulation of distinctive T-urf13 mitochondrial transcripts. Rf8-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 Rf* is positioned within this PPR cluster as well as Rf3, which restores USDA (S)-cytoplasm maize. Partially male-fertile plants segregated for the presence or absence of the Rf8-associated T-urf13 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 Rf8-mediated male fertility is under the control of more than one nuclear locus.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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