Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 29, 2004
Publication Date: September 1, 2004
Citation: Jan, C.C., Tan, A.S., Gulya Jr, T.J. 2004. Registration of four downy mildew resistance sunflower germplasms. Crop Science. 44:1887. Interpretive Summary: Wild sunflower species are valuable genetic sources for the improvement of cultivated sunflower. Sunflower downy mildew (SDM) is one of the most damaging sunflower diseases and race 4 is the predominant race of SDM in the USA. Four sunflower germplasms with resistance to race 4 of SDM were derived from hybridization between susceptible inbred line HA 89 and four highly resistant wild accessions. These germplasms will provide diversity for genetic resistance to the prodominant race of sunflower downy mildew in the USA, and are available for use in sunflower breeding and genetic programs.
Technical Abstract: Four sunflower (Helianthus annuus L.) germplasms PLH1, PLH2, PLH3,and PLH4, with resistance to race virulence phenotype 730 (Race 4) of sunflower downy mildew (DM 730), [caused by Plasmopara halstedii (Farl.) Berl. & de Toni in Sacc.], were cooperatively developed and released by the USDA-ARS and the North Dakota Agricultural Experiment Station. The germplasms were derived from hybridization between the susceptible inbred line HA 89 and four highly resistant wild H. annuus accessions. Resistant plants from the wild H. annuus populations were crossed as females with HA 89. F1 plants resistant to DM 730 were backcrossed to cms HA 89. Male-fertile BC1F1 plants showing resistance to DM-730 were backcrossed a second time to HA 89. For each wild species source, a single resistant plant was crossed to HA 89 to produce the F1, BC1F1, and BC2F1 generations. One resistant BC2F1 plant from each accession was self-pollinated. More than 60 random BC2F2 plants from each accession were self-pollinated to produce BC2F3 seeds for distribution. Each germplasm population, in the BC2F3 generation, is expected to have resistant gene frequency of approximately 50%. These germplasm populations have 87.5% cultivated H. annuus and 12.5% wild H. annuus nuclear genes in HA 89 cytoplasm. Most plants in these germplasms are single-headed and self-compatible. Seeds are either black or black with white stripes.