Phylogenetic position of Raphanus in relation to Brassica species based on 5S rRNA spacer sequence data

Based on RFLP analysis, two evolutionary lineages for Brassica diploid species have been proposed. These are (I) the “nigra” lineage and (II) the “rapa/oleracea” lineage. The phylogenetic relationship of Raphanus species to these two lineages is still unclear because chloroplast and mitochondrial DNA genomic restriction site variation suggests that Raphanus is more closely related to the “rapa/oleracea” lineage, whereas nuclear RFLPs and other lines of evidence suggest that Raphanus belongs to the “nigra” lineage. Here, we present evidence of the intergenic spacer of nuclear 5S rRNA to support that Raphanus is more closely related to the “nigra” lineage than to the “rapa/ oleracea” lineage. Genetic polymorphism within species is also discussed.