Author
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Seiler, Gerald |
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Gulya Jr, Thomas |
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Submitted to: Sunflower International Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 7/15/2004 Publication Date: 8/29/2004 Citation: Seiler, G.J., Gulya Jr., T.J. 2004. Exploration for wild Helianthus species in North America: Challenges and opportunities in the search for global treasures. International Sunflower Conference Proceedings. v. 1. p. 43-68. Interpretive Summary: Exploration and collection of wild relatives of cultivated sunflower represents one of the more difficult and challenging activities in the process of conserving genetic diversity. The genus Helianthus (sunflower) has 51 species, 14 annual and 37 perennial. Over the past several decades genes for resistance to several diseases such as rust, downy mildew, powdery mildew, broomrape, Sclerotinia (white mold) head and stalk rot, and resistance to insects such as sunflower moth have been identified from the wild Helianthus species and successfully transferred into cultivated sunflower. The estimated economic value of the wild species' contribution to cultivated sunflower varies from $269.5 to $384 million annually. The USDA-ARS formally established a wild Helianthus collection at Bushland, Texas, in 1976. Having the wild species of Helianthus within the boundaries of the USA has facilitated the collection of sunflower species. The explorations for wild sunflowers over the past 30 years have resulted in the assemblage of a USDA-ARS collection that is the most complete collection in the world. It is presently located at the National Plant Germplasm System Plant Introduction Station at Ames, Iowa. Currently, the wild Helianthus collection contains 2163 accessions, about two-thirds of which are annual species. The sunflower genus (Helianthus) is an extremely diverse group of species whose geographic distribution ranges from nearly universal in all the continental United States, to species which are found only in few locations or in threatened habitats. Aggressive collection of wild sunflower species for preservation in seed banks is critical so that it will be readily available to the sunflower genetics and breeding community. Furthermore, given the tenuous situation of wild species populations in nature, seed banks may provide the only way to preserve some wild species populations for posterity. Their collection and preservation will ensure the preservation of the rarer Helianthus species in threatened habitats. While we have representative populations of most species, we do not have the total genetic diversity available. There is a need to collect additional populations of wild sunflower species. Future plans are to systematically add species populations to the germplasm collection. Assuming one collecting trip per year, it may be possible to collect seed of all remaining species within the next decade. By doing so, we can pass on to future generations a diverse collection of wild Helianthus species which can be used to improve cultivated sunflower in the future. Technical Abstract: The genus Helianthus has 51 species, 14 annual and 37 perennial. The wild sunflower species have contributed many agronomically important traits to cultivated sunflower. The estimated economic value of their contribution to cultivated sunflower varies from $269.5 to $384 million annually. The USDA-ARS formally established a wild Helianthus germplasm collection at Bushland, Texas, in 1976. Having the wild species of Helianthus within the boundaries of the USA has facilitated the collection of sunflower germplasm. The explorations for wild sunflowers over the past 30 years have resulted in the assemblage of a USDA-ARS collection that is the most complete collection in the world. It is presently located at the National Plant Germplasm System Plant Introduction Station at Ames, Iowa. Currently, the wild Helianthus collection contains 2163 accessions, about two-thirds of which are annual species. Aggressive collection of wild sunflower germplasm for preservation in seed banks is critical so that germplasm may be readily available to the sunflower genetics and breeding community. Furthermore, given the tenuous situation of wild species populations in nature, seed banks may provide the only way to preserve some wild populations or species for posterity. The genus Helianthus is an extremely diverse group of species whose geographic distribution ranges from nearly universal in all the continental United States, to species which are found only in few locations or in threatened habitats. While we have representative populations of most species, we do not have the total genetic diversity available. There is a need to collect additional populations of wild sunflower species. Currently, 37 of the 65 taxa are either not available due to low seed supplies or have few accessions for research. Future plans are to systematically add species populations to the germplasm collection. Assuming one collecting trip per year, it may be possible to collect seed of all remaining 36 taxa within the next decade. The sunflower research community has an opportunity to collect and preserve the unique genetic resources of the wild relatives of Helianthus and to pass it on to future generations to be used for improving cultivated sunflower. |
