Graduate Student HundsonAlpha Institue for Biotechnology Huntsville, Alabama
Body of Abstract: Polyploidy has been shown to play a role in the domestication and diversification of several crops. Domesticated for over 200 years for their showy blooms, the common garden dahlia, Dahlia variabilis, is no exception with over 54,000 diverse cultivars. This diversity is likely driven in part due to its octoploid genome, but the polyploid history and parentage of D. variabilis remain unknown. Several hypotheses about the parentage and history of polyploidy have been proposed based on crossing experiments and cytology, suggesting that two tetraploid species underwent hybridization and a whole genome duplication to form D. variabilis. However, due to the polyploid nature and large genome sizes of Dahlia, these phylogenetic relationships remain unresolved. Here we address this question in three ways: by generating 1) a bait-capture multi-locus phylogeny of all Dahlia species, 2) high coverage Illumina short reads of four hypothesized tetraploid parental species based on floral color chemistry, 3) a PacBio HiFi reference genome for an octoploid 6 Gbp D. variabilis cultivar Edna C. These data support the hypothesis that octoploid D. variabilis is derived from both an auto- and allo- polyploidization events. To identify the parental lineages, we are currently analyzing Illumina genome shotgun SNP and coverage variation from these four putative tetraploid parental species against the octoploid D. variabilis reference genome. A deeper understanding of the evolutionary and polyploid history, in addition to the genomic resources we have generated, have large potential to improve breeding resources for the cultivated dahlia.