Petaloid-type cms in carrot is not associated with expression of atp8 (orfB).
Two different atp8 reading frames with divergent C-terminal extensions were identified in a sterility-inducing mitochondrial type (mitotype) of carrot; examination of three fertility-inducing mitotypes revealed atp8 reading frames that were either terminated at a position conserved among other plant atp8 genes or continued with unique C-terminal extensions. Similarities between the C-terminal extensions suggest ancient common ancestry, but the level of sequence divergence implies lack of functional conservation. Northern analysis indicated that the C-terminal extensions are transcribed and are present within the primary atp8 transcripts. Western analysis revealed that the products of the two extended atp8 reading frames encoded by the sterility-inducing mitotype are significantly smaller than those predicted by complete translation of their C-terminal extensions, but are slightly larger than the products from unextended reading frames. No alterations were observed in atp8 transcripts or proteins isolated from flowers of the sterility-inducing mitotype that were phenotypically fertile as a result of segregation for nuclear fertility-restoring Ms or Rf alleles, and thus, there is no evidence that expression of atp8 is directly involved in the petaloid cms phenotype in carrot.
Robison
Mary M
MM
Department of Plant Agriculture, Bovey Bldg., University of Guelph, Guelph, ON N1G 2W1, Canada. mrobison@uoguelph.ca
Wolyn
David J
DJ
D020413:3' Untranslated Regions; D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D017124:Conserved Sequence; D004272:DNA, Mitochondrial / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D018552:Daucus carota / Q000235:genetics*; D015870:Gene Expression; D017343:Genes, Plant; D008928:Mitochondria / Q000145:classification; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D012098:Reproduction / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D020413:3' Untranslated Regions; D004272:DNA, Mitochondrial; D018744:DNA, Plant; D010940:Plant Proteins; D018749:RNA, Plant