Case Study: Sunflower Domestication and Breeding
Patrick Byrne, Department of Soil and Crop Sciences, Colorado State University, Fort Collins, Colorado 80523<EMAIL_ADDRESS>Laura Marek, Agronomy Department, Iowa State University, North Central Regional Plant Introduction Station, Ames, Iowa 50014
Outline
- Introduction
- Distribution of wild sunflower species
- Conservation of wild sunflower species
- Domestication and early improvement of sunflower
- Use of wild relatives in sunflower breeding
- References
- Acknowledgments
1. Introduction
Sunflower (Helianthus annuus L.) is one of the few major food crops that was domesticated in what is now the United States. Although its center of origin was in the U.S., early improvement of the crop occurred in Russia. Sunflower is now an important source of oil, seeds for snacking, and bird feed, in addition to being a popular garden ornamental. It is grown commercially in 72 countries and covers over 23 million hectares (Seiler et al., 2017). Wild sunflower relatives have been an important source of variation in sunflower since the early 20th century.
2. Distribution of wild sunflower species
As described by Dr. Laura Marek in the video that follows, wild sunflowers are widely distributed across North America, including in nearly every state in the U.S., as well as Canada and Mexico. The distribution of wild sunflower taxa across North America is shown in Figure 1, and some example are shown in Figures 2–5. Habitats of wild sunflower relatives are extremely diverse, and include grasslands, forests, swamps, deserts, roadsides, and farmers’ fields (Seiler et al., 2017).
Figure 1. Distribution of wild sunflower taxa across North America. Map provided by Dan Carver and Colin Khoury.
Video 1. What is the natural distribution of sunflower crop wild relatives?
Figure 2. (Left) Wild H. annuus in Southern Utah near Grand Staircase Escalante National Monument. Photo credit: Laura Marek. (Right) H. annuus growing south of Lone Pine, California, in the shadow of Mt. Whitney. Photo credit: Laura Marek.
Figure 3. (Left) Helianthus niveus ssp. niveus, growing in dunes along the Pacific Ocean west of Vicente Guerrero, about 95 miles south of Ensenada, Baja California. This annual species occurs only in Mexico, and is the only Helianthus taxa unrepresented in the U.S. National Plant Germplasm System. Photo credit: Laura Marek. (Right) Helianthus radula growing in a field plot in Parlier, California. This species typically does not have sunflower’s typical bright yellow ray flowers, although occasionally a population will have plants with rudimentary rays, as shown in this image. Photo credit: Laura Marek.
Figure 4. Two views of Helianthus salicifolius north of Lake Lawtonka, northwest of Lawton, Oklahoma. This is the southernmost collection location of this perennial species, which has unusually narrow leaves. Photo credit: Laura Marek.
Figure 5. Helianthus paradoxus along the north edge of the Blue Hole Cienega Nature Rese