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.
Department of Plant Agriculture, Bovey Bldg., University of Guelph, Guelph, ON N1G 2W1, Canada. mrobison@uoguelph.ca
Mary M
MM
Robison
David J
DJ
Wolyn
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