Registration of Three Confection Sunflower Germplasm, HA-DM2, HA-DM3, and HA-DM4, Resistant to Downy Mildew and Rust

Downy mildew (DM) and rust are two destructive diseases in sunflower (Helianthus annuus L.) production worldwide that limit yield and reduce seed quality. Combining different disease resistance (R) genes in a single genotype of sunflower can increase the field performance due to host resistance. The confection sunflower germplasm lines HA-DM2 (Reg. No. GP-350, PI 687022), HA-DM3 (Reg. No. GP-351, PI 687023), and HA-DM4 (Reg. No. GP-352, PI 687024), developed using backcrossing, pedigree breeding, and DNA marker-assisted selection, were released by the USDA-ARS Sunflower and Plant Biology Research Unit in collaboration with the North Dakota Agricultural Experiment Station in June 2017. HA-DM2 harbors the DM R gene, Pl(Arg), and rust R gene, R-12, both transferred from an oilseed sunflower line RHA 464. HA-DM3 harbors the DM R gene, Pl(17), and rust R gene, R-13a, transferred from an oilseed line HA 458 and confection line HA-R6, respectively. HA-DM4 harbors the DM R gene, Pl(18), and rust R gene, R-13a, transferred from an oilseed line HA-DM1 and confection line HA-R6, respectively. Phenotypic and marker testing for DM and rust confirmed that the BC4F4-derived HA-DM2, HA-DM3, and HA-DM4 germplasm each harbors DM and rust R genes in the homozygous condition and are resistant to all DM and rust races identified in North America to date. These disease-resistant lines are a valuable contribution for breeding-enhanced DM and rust resistance in confection sunflower in North America and globally.