Submitted to: International Conference on Industrial Crops and Rural Development Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2005
Publication Date: 9/17/2005
Citation: Seiler, G.J. 2005. Wild annual Helianthus anomalus and Helianthus deserticola as potential sources of improved oil content and quality in cultivated sunflower. Proceedings of 2005 Annual Meeting of the Association for the Advancement of Industrial Crops: Iternational Conference on Industrial Crops and Rural Development, September 17-21, 2005, Murcia, Spain. p. 681-687. Interpretive Summary: The disappearance of habitat for several wild sunflower species is of concern for the long-term survival of the sunflower industry because wild species are the ancestors of the crop. The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from the wild species, which have provided a continuous source of desirable agronomic traits. Therefore, it is imperative that as many natural populations of wild species as possible be collected and preserved in germplasm collections for future use. There has been an increased interest in breeding sunflower for increased oil content and improved oil quality. Sand sunflower (Helianthus anomalus) and desert sunflower (Helianthus deserticola) are excellent candidates for oil quantity and quality based on their adaptation to desert environments. Unfortunately, due to the demand for the seed of these species and the difficulties of regenerating the original populations, seed has not been available for research for almost 25 years. The objective of the present study was to undertake an exploration to the desert southwest US to collect seeds of the two desert species for the USDA-ARS sunflower germplasm collection and make them available for further research. The sunflower exploration covered 2550 miles in Utah, Arizona, and Nevada, during September of 2000. It was an extremely dry year, with no evidence of either species being present in many of the fragile sandy habitats visited 20 years ago. For whatever reason, only three populations had plants with seeds for collection in 2000, one population of the desert sunflower and two populations of the sand sunflower. The desert sunflower population had a typical oil content of 33%, compared to 45% for cultivated sunflower, while the populations of the sand sunflower had a very high oil content of 43 to 46%, the highest ever observed in any wild sunflower species. The fatty acid profile of the sand sunflower was high in linoleic acid content for a desert environment, approaching 70%, while the linoleic acid concentration in the desert sunflower of 54% is more typical of what one would expect to observe in a desert environment. The saturated palmitic and stearic fatty acids in sand sunflower were about 25% less than in cultivated sunflower oil. There appears to be adequate variability in this wild species to breed for a reduced level of the saturated fatty acids in cultivated sunflower oil. The sand sunflower has the largest seed and the highest oil concentration of any of the wild sunflower species. They also have the same number of chromosomes as cultivated sunflower. This will facilitate the breeding process when the wild germplasm is introgressed into cultivated germplasm for further screening for drought tolerance traits. The addition of these populations of wild species to the wild sunflower germplasm collection will insure their preservation for the future, and will greatly increase the available genetic diversity for improving the cultivated sunflower, keeping it a viable and competitive global crop.
Technical Abstract: The genus Helianthus is composed of 51 species and 19 subspecies with 14 annual and 37 perennial species. The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from the wild species, which have provided a continuous source of unique agronomic traits. Interest in using wild species in breeding programs has increased, but concerns about the introgression of low oil concentration and quality from the wild species persist. Helianthus anomalus Blake and H. deserticola Heiser are excellent candidates for oil concentration and quality improvement based on their desert environment. Unfortunately, due to the demand for achenes of these species and the difficulties of regenerating the original populations, achenes have not been available for research for almost 25 years. This report documents an exploration to the desert southwest USA to collect achenes of the two desert species and the initial assessment of their potential for improving oil content and quality in cultivated sunflower. The sunflower exploration took place from September 16 to 23, 2000. The exploration covered 4100 kilometers in three states, Utah, Arizona, and Nevada. The H. deserticola population had an average oil concentration of 330 g/kg, while the populations of H. anomalus had very high oil contents of 430 and 460 g/kg, respectively, the highest ever recorded in any wild sunflower species. The linoleic fatty acid concentration in the oil of H. anomalus populations was uncharacteristically high for a desert environment, approaching 700 g/kg. A linoleic acid concentration of 540 g/kg in H. deserticola was more typical for that fatty acid in a desert environment. Helianthus anomalus has the largest achenes and the highest oil concentration of any of the wild sunflower species, and the same chromosome number (2n=34) as cultivated sunflower. These features will facilitate the introduction of genes from this wild annual progenitor into cultivated sunflower. The lower saturated fatty acid profile in this species is also a desirable trait offering the potential to reduce saturated fatty acids in cultivated sunflower. Further research will be needed to determine the inheritance of the fatty acids and oil content. Other agronomic traits will need to be monitored during the introgression of these traits into cultivated sunflower.