ARS | Publication request: Registration of the restorer oilseed sunflower germplasm RHA 464 possessing genes for resistance to downy mildew and sunflower rust

Submitted to: Journal of Plant Registrations
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 29, 2010
Publication Date: August 12, 2010
Repository URL: http://naldc.nal.usda.gov/catalog/45959
Citation: Hulke, B.S., Miller, J.F., Gulya, T.J. 2010. Registration of the restorer oilseed sunflower germplasm RHA 464 possessing genes for resistance to downy mildew and sunflower rust. Journal of Plant Registrations. 4:249-254.

Interpretive Summary: Sunflower rust has historically been a disease of moderate importance in sunflower, with major outbreaks occurring in years with ideal conditions for the pathogen. Within the sunflower breeding community, there is a need for additional sources of rust resistance in light of recent disease outbreaks in 2008 and 2009, which limited yield and quality of the crop. Downy mildew is another disease that has a consistent effect on reducing crop yield nearly every year. The development and release of RHA 464 by the USDA-ARS Sunflower Unit was in response to input from stakeholder groups including producers, grain and oil marketers, and seed companies, who indicated that rust and downy mildew resistance need to be included together in commercial hybrids to sustain sunflower yield. Prevention of losses in commercial grain production, in terms of both grain yield and oil yield, is critical to sustainable sunflower production throughout the product chain. The release of RHA 464 will partially fill this need, however, further resistance gene introduction and targeted gene stacking will still be required in the future to maintain resistance for both diseases.

Technical Abstract: Sunflower rust (caused by Puccinia helianthi Schw.), has historically been a disease of moderate importance in sunflower, with major outbreaks occurring in years with ideal conditions for the pathogen. Within the sunflower breeding community, there is a need for additional sources of rust resistance in light of recent disease outbreaks. At the same time, resistance to downy mildew (caused by Plasmopara halstedii [Farl.] Berl. & De Toni) is also critical to parental line development because of the major impact of this disease over years. Our objective was to produce a restorer sunflower germplasm with resistance to the most virulent race of sunflower rust, Race 777, and combine with it the best currently available downy mildew resistance in a high-yielding genetic background. We achieved this objective by using the pedigree breeding method with early generation selection for rust and downy mildew resistance and late generation testcross evaluation for yield. The resulting restorer oilseed sunflower (Helianthus annuus L.) germplasm, RHA 464 (Reg. No. _; PI 655015; experimental ’05 187’), has been released with resistance to the three pathogens of interest by the USDA-Agricultural Research Service, and the North Dakota Agricultural Experiment Station, Fargo, ND, to fill the urgent need in the sunflower industry for breeding lines with elite genetic background and disease resistance.