Author
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Seiler, Gerald |
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MAREK, LAURA - Iowa State University |
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Submitted to: Sunflower International Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 12/15/2011 Publication Date: 2/27/2012 Citation: Seiler, G.J., Marek, L.F. 2012. Collection and evaluation of wild perennial Helianthus pumilus achenes for oil concentration and fatty acid composition. In: 18th International Sunflower Conference Program and Abstracts, Mar del Plata & Barcarce, Argentina, February 27-March 1, 2012. P.175. Interpretive Summary: 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 agronomic and economic traits for cultivated sunflower. The genus Helianthus consists of 52 species and 19 subspecies with 14 annual and 38 perennial species. Recent emphasis on the concentration and fatty acid composition of sunflower oil as it related to healthy hearts has increased interest in using wild species in breeding programs to improve oil quality. The objective of the study was to undertake an exploration of Colorado and Wyoming, USA to collect achenes from the entire distributional range of dwarf sunflower (Helianthus pumilus) and assess the potential of the populations for improving oil content and quality in cultivated sunflower. The exploration was successful in collecting 45 representative populations of dwarf sunflower from its entire distributional range with 29 populations collected in Colorado and 20 from Wyoming. The populations from Colorado had an average oil content of 24.9 %, while populations from Wyoming averaged 25.2 %. The overall average oil content was 25.1 %, considerably lower than cultivated sunflower, which averages 47.0 %. The low oil content of this species can be increased by backcrossing to a high oil hybrid. The average linoleic acid concentration approached 75.0 %, much higher than the 54.0 % expected from a semi-arid environment. The linoleic acid concentration averaged 74.8 % for Colorado and 75.4 % for Wyoming. The corresponding oleic aid concentration averaged 12.7 % for Colorado and 12.3 % for Wyoming, with an overall average of 12.5 %. The higher concentrations of linoleic acid in dwarf sunflower could be a potential source of genes for increasing linoleic acid concentration in traditional sunflower oil when grown in a warm climate. The combined saturated palmitic and stearic fatty acids in dwarf sunflower averaged 10.2 %, about equal to traditional cultivated sunflower oil that averages 11.0 %. 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. The addition of 45 populations of dwarf sunflower 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 oilseed crop. Technical Abstract: The genus Helianthus consists of 52 species and 19 subspecies with 14 annual and 38 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 continued source of desirable agronomic traits. There has been an increased interest in using wild species in breeding programs, but there have been concerns about the introgression of low oil content and quality from the wild species. Helianthus pumilus (Dwarf sunflower) is a perennial species with the potential to improve oil and fatty acid composition improvement based on its xerophytic habitat. The objective of the study was to undertake an exploration to Colorado and Wyoming, USA to collect achenes from the entire distributional range of H. pumilus and assess the potential of the populations for improving oil content and quality in cultivated sunflower. The sunflower exploration took place from August 7 to August 19, 2005 and covered 5150 kilometers in Colorado and Wyoming. Achenes of 49 populations were collected and deposited in the wild sunflower germplasm collection at the USDA-ARS, NPGS, North Central Regional Plant Introduction Station, Ames, Iowa, where they are maintained and distributed. Voucher specimens are maintained at the USDA-ARS wild sunflower species herbarium at Fargo, North Dakota. Achenes were collected from 10 to 100 plants within each population and were bulked into a single sample. For each population, a composite sample of 10 randomly sampled achenes was analyzed for fatty acid composition using organic base-catalyzed transesterification of fatty acid methyl esters and capillary gas chromatography. Oil content was determined on a 2-ml achene sample using nuclear magnetic resonance. The exploration was successful in collecting representative populations from the entire distributional range. The H. pumilus populations had an average oil content of 25.4%, considerably lower than cultivated sunflower, which averages 45% oil. The highest oil content of an H. pumilus population was 29.4%. The linoleic acid concentration approached 75%, much higher than the 55% expected from a semi-arid environment. The combined saturated palmitic and stearic fatty acids in H. pumilus averaged 10.2%, close to cultivated sunflower which has an average of 11.5%. The higher concentrations of linoleic acid indicate that H. pumilus could be a potential source of genes for increasing linoleic acid concentration in traditional sunflower oil grown in southern latitudes. The low oil content of this species can be increased by backcrossing to a high oil cultivar. Further research will be needed to determine the inheritance of the fatty acid and oil content traits. |
