Evaluation of sunflower breeding material for resistance to downy mildew (Plasmopara halstedii)

Abstract

Background and Aim. Stable sunflower production depends on the use of breeding material resistant to major pathogens. Downy mildew (DM), caused by the oomycete Plasmopara halstedii, remains an important disease of sunflower. The aim of this study was to evaluate sunflower pollen fertility-restorer lines with different levels of inbreeding and identify genotypes with high field resistance to DM under the conditions of East Kazakhstan.
Materials and Methods. Field phytopathological screening of breeding material was conducted during 2021–2024. In 2023, high soil moisture combined with marked diurnal temperature fluctuations created a natural provocative background. Competitive allele-specific PCR (KASP) using the P_larg and P18 marker systems was applied for molecular evaluation of the breeding material.
Results. Visual symptoms of downy mildew were absent in 2021, 2022, and 2024. The widespread disease development observed in 2023 enabled differentiation of the breeding material and culling of susceptible genotypes. Lines with high field resistance to the local Plasmopara halstedii population were identified, and resistant signals for the Pl_arg and P18 marker systems were detected in a number
of progenies.
Conclusion. The selected fertility-restorer lines are of practical interest as source material for further breeding of downy mildew-resistant sunflower hybrids and adapted to the regional conditions.