Sunflower downy mildew, caused by Plasmopara halstedii, is one of the most aggressive diseases affecting this crop, causing significant losses ranging between 20% and 80%, depending on the pathogen race, the crop development stage, and the hybrid's susceptibility. Curently, sunflower breeding programs focused on obtaining resistance genes, which has induced pressure for the development of increasingly aggressive races. While initially we spoke of races such as race 100 or 300, currently we can discuss race 730, 734, and even in some cases, race 774 or 777. Race 730, used in our study, is among the most widespread races in Europe, exhibiting a high capacity for adaptation and for overcoming the resistance conferred by the genes Pl1, Pl2, Pl3, Pl4, Pl9, Pl10, Pl11, and Pl12, which are not sufficient to provide the genotype with resistance to this race.In our study, genotypes derived from interspecific crosses of wild sunflower species were selected. Following the research, protocols were established to determine the optimal timing for embryo inoculation, with the goal of improving the efficiency of the methods used for detecting resistance or susceptibility. The results obtained indicated a higher success rate of inoculation when the embryo radicle was between 0.5 and 2 mm, with the inoculation rate gradually decreasing as the embryo developed. The study also allowed for the creation of new sunflower genotypes resistant to race 730, with the prospect that these lines may be registered in international gene banks in the future.

Plasmopara halstedii ,race 730 ,phenotypic screening ,optimized protocol ,plant breeding

agronomy

Presentation: poster