| The cytoplasmic male sterility phenotype manifests itself as aborted pollen or other non-functional male sexual structures in the flower of higher plants. This is an agronomically useful trait and in wheat is produced by crossing the female parent, Triticum timopheevi, with the male parent, T. aestivum. The cytoplasmic male sterility trait is generated by a nuclear-mitochondrial incompatibility of the two species since both parents are fertile.; The mitochondrial DNA of cms and fertile wheat was isolated and subjected to restriction enzyme analysis. Southern blots were generated and hybridized to probes specific to the S-episomes of maize mitochondria and genes of wheat mitochondria. RFLP's were noted to sequences that hybridize to the S-2 episome probe, cob, and coxI. Minor or no differences were found using the S-1 episome probes, 5{dollar}spprime{dollar}-exon of coxII, and intron of coxII.; A mitochondrial DNA library of cms wheat was made. Two clones that responded to the coxI probe were selected from the library and subjected to DNA sequencing.; Sequencing revealed the presence of an open reading frame, orf256, preceding and unique DNA at the 3{dollar}spprime{dollar}-flanking region of coxI. orf256 retained all the upstream sequences of coxI of fertile wheat and 33 of the first 34 nucleotides of coxI of cms and fertile wheat. orf256 and coxI are separated by 114 bp.; These sequences were subcloned and hybridized to Southern blots of mtDNA, cpDNA, and nDNA of cms and fertile wheat. orf256 is probably not found in cpDNA and nDNA of cms and fertile wheat. orf256 is not repeated in the mtDNA of cms wheat and probably not found in mtDNA of T. aestivum. The 3{dollar}spprime{dollar}-flanking region of coxI also appears not to be present in cpDNA and nDNA of cms wheat nor T. aestivum. The 3{dollar}spprime{dollar}-flanking sequences are repeated in the mtDNA of cms wheat and present once in the mtDNA of T. aestivum. |
