Sorghum mitochondrial orf25 and a related chimeric configuration of a male-sterile cytoplasm.
We describe fundamental characteristics of sorghum mitochondrial orf25, urf209, and a related chimeric configuration, orf265/130, which is restricted to the IS1112C source of cytoplasmic male sterility in sorghum. Transcripts of urf209 are edited at ten nucleotides, resulting in nine amino-acid changes predicted from genomic sequences. The cDNA-predicted polypeptide product is 23.6 kDa, while Western blot analyses identify a product of 20k Da. Transcription of urf209 is characterized by one or two transcripts, dependent on nuclear background, but this difference is not related to male fertility status. The orf265/130 chimeric region includes 288 bp 95% identical to sequences 5' to maize T-cytoplasm T-urf13 and atp6, which includes a common transcription initiation site, and terminates with a recombinational event involving urf209. The urf209 similarity extends 189 bp, followed by sequences duplicated 5' to sorghum atp6-2. Sequences immediately 3' to the atp6-2 similarity include a second in-frame start codon, defining orf130. Structural features 5' to orf130 are shared with motifs found 5' to several translated mitochondrial open reading frames. The orf265/orf130 configuration is uniquely transcribed, and transcripts of orf130 exhibit one silent RNA editing event. Transcription in somatic cells is not altered by male fertility status.
Van Tang
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Department of Plant Pathology and Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32611, USA.
Pring
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Muza
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Yan
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D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D002523:Edible Grain / Q000235:genetics* / Q000502:physiology; D017343:Genes, Plant; D008928:Mitochondria / Q000235:genetics*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic
D018076:DNA, Complementary; D004272:DNA, Mitochondrial; D018744:DNA, Plant; D024101:Mitochondrial Proteins; C098557:Orf25 mitochondrial protein, plant; C098558:Orf265 protein, Sorghum bicolor; D010940:Plant Proteins