Sequence analysis of a chloroplast intergenic spacer for phylogenetic estimates in Allium section Cepa and a PCR-based polymorphism detecting mixtures of male-fertile and male-sterile cytoplasmic onion

Abstract

Restriction-enzyme analysis of the chloroplast (cp) DNA yielded maternal phylogenies supporting a close phylogenetic relationship among normal (N) male-fertile and male-sterile (S) cytoplasmic bulb onion (Allium cepa), Allium altaicum, Allium fistulosum, Allium galanthum, Allium roylei, and Allium vavilovii. The S cytoplasm of onion is most likely an alien cytoplasm introduced in antiquity into onion populations. We previously showed that size differences in an intergenic spacer in the cp DNA distinguish N and S cytoplasms of onion. We cloned and sequenced this intergenic spacer from the N and S cytoplasms of onion, A. altaicum, A. fistulosum, A. galanthum, Allium pskemense, Allium oschaninii, A. roylei, and Allium ampeloprasm (outgroup) to identify the nature of previously described RFLPs and to develop a PCR-based marker revealing N-cytoplasmic contamination of S-cytoplasmic hybrid seed lots. Phylogenies based on restriction-enzyme analysis of the entire cp DNA were similar, but not identical, to those based on sequence divergence in this intergenic region.