Registration of HA-DM12, HA-DM13, and HA-DM14 oilseed sunflower germplasms with resistance to sunflower downy mildew and rust

Downy mildew (DM) and rust are two major global sunflower (Helianthin annuus L.) diseases causing significant yield losses and reducing seed quality. Host plant resistance mediated by dominant race-specific genes has been extensively used in sunflower production to control these diseases. However, the considerable variability of the DM and rust pathogens caused by mutation or recombination has changed the dynamics of the diseases, significantly increasing their incidence in recent years. This necessitates the development and release of sunflower germplasm with enhanced levels of disease resistance. Germplasm lines HA-DM12 (Reg. no. GP-382, PI 700006), HA-DM13 (Reg. no. GP-383, PI 700007), and HA-DM14 (Reg. no. GP-384, PI 700008), all with multiple DM and rust resistance, were developed using phenotypic evaluation and marker-assisted selection. The three lines share a common DM gene (Pl_Arg) and a rust gene (R₁₂) and a combination of different DM genes (Pl₈, Pl₁₇, and Pl₁₈, respectively). The triple-gene pyramids—HA-DM12 (Pl₈Pl₈/Pl_ArgPl_Arg/R₁₂R₁₂), HA-DM13 (Pl₁₇Pl₁₇/Pl_ArgPl_Arg/R₁₂R₁₂), and HA-DM14 (Pl₁₈Pl₁₈/Pl_ArgPl_Arg/R₁₂R₁₂)—confer comprehensive resistance to all races of DM and rust identified so far and can be used in sunflower breeding programs to develop hybrids with durable resistance to DM and rust.