Brent Hulke, Jerry Miller, Thomas Gulya Jr. and Brady Vick
Abstract: Within the sunflower (Helianthus annuus L.) breeding community, there is a need for additional sources of downy mildew [caused by Plasmopara halstedii (Farl.) Berl. & De Toni] resistance to combat economically damaging races in North America. Our objective was to produce three genetic stocks, each with a different source of downy mildew resistance, in the genetic background of HA 434, a recently released sunflower maintainer germplasm with high oleic fatty acid content in the seeds. We used the backcross and pedigree breeding methods, with HA 434 as a recurrent parent. Gas chromatography analysis of seed oil composition and greenhouse testing of downy mildew resistance were used during the development process and for progeny testing of the finished genetic stocks. As a result, three oilseed sunflower genetic stocks, HA 458 (Reg. No. GS-51; PI 655009), HA 459 (Reg. No. GS-52; PI 655010), and HA 460 (Reg. No. GS-53; PI 655011), have been released which are resistant to downy mildew and possess a high-oleic fatty acid profile in the seed oil. The experimental designations for HA 458, HA 459, and HA 460 were 06GH 116-9, 06GH 113-4, and 05GH 138-4, respectively. These genetic stocks were released by the USDA–ARS and the North Dakota Agricultural Experiment Station, Fargo, ND, to fill the urgent need in the sunflower industry for donor lines with elite genetic background and The USDA–ARS and the North Dakota Agricultural Experiment Station, Fargo, ND, have developed and released three oilseed sunflower (Helianthus annuus L.) genetic stocks, HA 458 (Reg. No. GS-51; PI 655009), HA 459 (Reg. No. GS-52; PI 655010), and HA 460 (Reg. No. GS-53; PI 655011), resistant to downy mildew [caused by Plasmopara halstedii (Farl.) Berl. & De Toni]. These genetic stocks were developed to provide diversity for resistance against downy mildew, a major sunflower disease under moist, cool environmental conditions. The sources of resistance for HA 458 and HA 459, which are PI 468435 and PI 435434, respectively, had not been used resistance to common races of downy mildew.
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