In situ hybridization with genomic and rDNA probes reveals complex origins for polyploid New Zealand species of Plantago (Plantaginaceae)

The cosmopolitan plant genus Plantago contains species with a wide range of chromosome numbers in its New Zealand endemic representatives. These species are diploid, tetraploid, octoploid, decaploid, dodecaploid and 16-ploid. Using genomic in situ hybridization, we have shown that some of these polyploids contain at least three different genomes, confirming their allopolyploid status. Fluorescence in situ hybridization with 5S and 45S rDNA probes showed a wide variety of species-specific patterns of distribution in the polyploid species, suggesting that polyploidy has been accompanied by genomic reorganization.