|Gobelman Werner, Karin|
Submitted to: Maize Genetics Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/1997
Publication Date: N/A
Technical Abstract: Cytoplasmic male sterility (CMS) systems have been found in over 150 plant species and are often attributed to chimeric open reading frames in the mitochondrial genome. Nuclear restorer (Rf) genes function to suppress the effects of CMS-associated mitochondrial abnormalities on male fertility. In some instances they accomplish this by altering the accumulation of CMS- -associated mitochondrial transcripts. It has been hypothesized that many of these altered transcripts arose via RNA processing activities encoded by the nuclear restorer genes. Rf8 is a newly-described restorer gene that can substitute for Rf1 to partially restore pollen fertility to male- sterile, T-cytoplasm maize. Although Rf8 is unlinked to the rf1 locus, it also alters T-urf13 transcript accumulation. Like the 1.6- and 0.6-kb T- urf13 transcripts that accumulate in T-cytoplasm plants carrying Rf1, 1.42- and 0.42-kb transcripts accumulate in plants that are partially restored by yRf8. Additionally, plants that carry Rf8 accumulate less URF13 protein than do their rf8 siblings. Another rare, weak restorer factor, Rf*, is associated with the accumulation of 1.4- and 0.4-kb T-urf13 transcripts. The consensus sequence, 5'-CNACNNU-3', is positioned adjacent to or overlapping the 5' nucleotides of the Rf1-, Rf8-, and Rf*-associated transcripts. This consensus also overlaps the 5' end of the 380- nucleotide, Rf3-associated orf107 transcript from CMS sorghum.