Mitochondrial gene diversity associated with the atp9 stop codon in natural populations of wild carrot (Daucus carota ssp. carota)

Mitochondrial genomes extracted from wild populations of Daucus carota have been used as a genetic resource by breeders of cultivated carrot, yet little is known concerning the extent of their diversity in nature. Of special interest is a SNP in the putative stop codon of the mitochondrial gene atp9 that has been associated previously with male-sterile and male-fertile phenotypic variants. In this study either sequence or PCR/RFLP genotypes were obtained from the mitochondrial genes atp1, atp9 and cox1 found in D. carota individuals collected from 24 populations in the eastern U.S. More than half of the 128 individuals surveyed had a CAA or AAA, rather than TAA, genotype at the position usually thought to function as an atp9 stop codon in this species. We also found no evidence for mitochondrial RNA editing (Cytosine to Uridine) of the CAA stop codon in either floral or leaf tissue. Evidence for intra-genic recombination, as opposed the more common inter-genic recombination in plant mit...