Exploring the Diversity of Wild Helianthus Germplasm for Ongoing Use in the Improvement of Sunflower

Breeding records indicate that germplasm from several wild Helianthus species has been employed for the breeding of biotic tolerances and for various important agronomic traits in elite sunflower cultivars. Here we use transcriptome sequence data to document the genetic location, length, and genomic distribution of some of these historic introgressions. However, much of the useful genetic variation in sunflower wild relatives remains to be exploited for sunflower improvement, especially that underlying abiotic tolerances. To assist in the selection of new material for introduction into cultivated genetic backgrounds, we employed Genotyping By Sequencing to assess the diversity of the genus and its various locally adapted taxa. A de novo genotyping algorithm identified over 10,000 SNPs that were used for phylogenetic and population genetic analyses. This magnitude of markers yields a more complete picture of the phylogenetic relationship of the different species and subspecies in the genus, and allows accurate placement of individual samples. Within species diversity is also explored, focusing on the primary wild progenitor of the crop H. annuus.  This information has allowed us to select wild germplasm for introgression into a cultivated genetic background in a way that maximizes the genetic diversity captured.