Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 2006
Publication Date: October 3, 2006
Citation: Seiler, G.J., Gulya, T.J., Marek, L.F. 2006. Exploration for wild Helianthus species from the desert southwest USA for potential drought tolerance. 7th European Conference on Sunflower Biotechnology, September 3-6, 2006, Gengenbach, Germany. SUNBIO2006. p. 17. Technical Abstract: In natural ecosystems, the ability of plants to survive environmental stress is probably more important than high achene productivity. During the process of selecting plants for high achene yield, sunflower breeders may have inadvertently lost some drought survival mechanisms common in wild sunflower species, therefore, cultivated sunflower could possibly benefit from an infusion of germplasm from the wild species to enhance drought tolerance. The genus Helianthus is comprised of 51 species and 19 subspecies, with 14 annual and 37 perennial species, all native to North America. The wild progenitors of the crop species could be potential sources for enhancing the rooting system of cultivated sunflower. The ability of some species to survive and thrive in shifting sand dunes with an annual precipitation of 50 mm could be of value for cultivated sunflower, which is often grown in arid areas. Unfortunately, due to the demand for the achenes of several desert species and the difficulties of regenerating the original populations, achenes from the USDA-Agricultural Research Service sunflower germplasm collection have not been available for almost 25 years. The objective of this study was to collect achenes (> 2,000 achenes per population) from as many populations as possible of desert species, annual H. anomalus (anomalous sunflower), H. deserticola (desert sunflower), H. niveus ssp. canescens (gray desert sunflower), and perennial H. niveus ssp. tephrodes (dune sunflower) from the desert southwest USA, and make them available for future research and improvement of cultivated sunflower. The first exploration took place from September 16 to 23, 2000 covering 4100 km in three states, Utah, Arizona, and Nevada, while the second exploration for desert sunflowers took place from February 26 through March 5, 2005, covering 2200 km in southern California and adjacent Arizona. Only one population of desert sunflower from Utah and two populations of anomalous sunflower from Utah were collected in 2000. It was an extremely dry year in 2000 with no evidence of the either desert species being present in the fragile sandy habitats where populations previously existed. In 2005, five populations of dune sunflower were collected from the Alogodones Dunes in California. The five populations represented the northern and southern extremes of the 40-mile-long dune system. One population of gray desert sunflower was collected from the Yuma Marine Corps Air Station, Yuma, Arizona, near the U.S.–Mexico border, with three additional populations from the Pinta Sands area of Arizona, which is the northernmost extension of the Gran Desierto of Sonora, Mexico. During the winter of 2005, unusually high rainfalls, in some areas up to five times the normal precipitation, produced a desert flora not observed for many years, affording the rare opportunity to collect these desert sunflowers in California and Arizona. However, the low achene set per head and the few flowering heads of the dune sunflower did not allow for an adequate collection of achenes for distribution from some of the populations. Additional achenes will have to be collected over time to obtain an adequate amount of achenes or the achenes collected will have to be increased through regeneration using bees as pollinators in isolation cages. The achene samples have been deposited at the USDA-ARS National Plant Germplasm System, North Central Regional Plant Introduction Station, Ames, Iowa, USA where they are maintained and distributed. The limited number of populations of desert sunflowers collected will provide a starting point for future research dealing with improving drought tolerance in cultivated sunflower.