Sunflower Genetic Resources—One of Our Native Crops.

Sunflower (Helianthus annuus L.) was domesticated in eastern North America approximately 5000 years ago. The breeding practices of Native Americans living in this region dramatically transformed sunflower. Starting from the wild progenitor H. annuus, a branched plant with many small heads and many small seeds of moderate oil content, early farmers derived the now familiar, non-branched crop plant that has one large head containing many large seeds of high oil content. The sunflower crop evolved along with the 53 species of crop wild relatives providing an important genus in which to study evolution and speciation, as well as providing a rich source of genetic diversity for crop improvement. The location of the crop wild relatives in North America has facilitated their collection with 28 explorations over the past 35 years building the USDA-ARS National Plant Germplasm System’s wild species collection to the largest extant collection in the world, serving as the center of distribution of crop wild relatives to the global sunflower community. Conservation of sunflower genetic resources is important, but utilization of the germplasm is also important for improving the crop. An overview of the activities related to the development of the collection, as well as the valuable traits that the crop wild relatives have contributed to the domesticated sunflower will be presented. Challenges currently facing germplasm collection and exchange will also be discussed.