Characterization of the wheat mitochondrial orf25 gene.

The wheat mitochondrial orf25 nucleotide sequence of 576 bp has been determined. Its derived protein sequence shares 88% and 75% amino acid identity with those of maize and tobacco mitochondria, respectively. The wheat and tobacco orf25 sequences lack four inserts, of 6 bp to 36 bp, that are present in the maize homologue. The wheat orf25 gene is actively transcribed and is preceded by a regulatory sequence block very similar to those located upstream of the wheat coxII and atp6 genes. Our observations support the view that orf25 sequences encode a functional polypeptide in plant mitochondria.