Microsatellite polymorphism among Chrysanthemum sp. polyploids: the influence of whole genome duplication

Polyploidy is common among flowering plants, including the Asteraceae, a relatively recent angiosperm group. EST-SSRs were used to characterize polymorphism among 29 Chrysanthemum and Ajania spp. accessions of various ploidy levels. Most EST-SSR loci were readily transferable between the species, 29 accessions were separated into three groups in terms of the number of fragments. It inferred that the formation from tetraploid to hexaploid and from octoploid to decaploid may be a recent event, while from the diploid to the tetraploid may be an ancient one in the Chrysanthemum lineage. EST-SSR polymorphism was found and some transcripts containing an SSR were transcribed differently in the de novo autotetraploid C. nankingense and C. lavandulifolium than in their progenitor diploid. EST-SSR could provide a potential molecular basis of adaptation during evolution, while whole genome duplication has a major effect on the mutational dynamics of EST-SSR loci, which could also affect gene regulation.