Evaluation of Sunflower Breeding Material for Resistance to Downy Mildew (Plasmopara halstedii)

Abstract

Blackground and Aim. Identification of sunflower inbred fertility restorer lines resistant to aggressive races of downy mildew (DM) in the East Kazakhstan region.

Materials and Methods. Field phytopathological screening of breeding material was conducted during the 2021–2024 period. Extreme hydrothermal conditions of May–June 2023 (soil waterlogging at 80–90% field capacity, diurnal temperature fluctuations of 10–15°C) served as a rigorous provocative background. The presence of target resistance loci (Рl₅, Рl₆,Рl₈, Pl_arg) was verified via PCR using STS and SSR markers.

Results. Visual symptoms of downy mildew were absent during climatically standard seasons (2021, 2022, 2024). The 2023 epiphytotic enabled differentiation of the material and strict culling of susceptible genotypes. Immune lines effectively resisting local races of the oomycete Plasmopara halstedii (including the 700 family and above) were successfully identified.

Conclusion. The identified resistant fertility restorer lines serve as valuable donors of effective Pl genes for the breeding of next-generation heterotic sunflower hybrids adapted to the bioclimate of the region.