RESEARCH ON GENETICS AND BREEDING FOR SUNFLOWER RESISTANCE TO PLASMOPARA HALSTEDII

Sunflower is attacked by more than 40 different diseases of which only a certain number causes serious reduction of seed yield. One of the most damaging diseases is downy mildew which is caused by Plasmopara halstedii fungus (Farl.) Berl.et de Toni (syn. Plasmopara helianthi Novit.). Sunflower downy mildew has a great economic importance in all countries where sunflower is grown. When the meteorological conditions during the vegetation period of sunflower become favorable for disease development, the damages produce considerable reducing of the seed yield and the oil content. The best way of controlling the fungus is to grow resistant cultivates and because that the major objective of this study was to developed sunflower genotypes genetically resistant to dominant races of downy mildew in Romania. During this work two co-dominant markers for Pl-6 and Pl-8 gene. For introduction of these genes in breeding program marker assisted selection (MAS) was used. Developed commercial sunflower inbred lines exhibit resistance to all known races of downy mildew in Romania indicated incorporation of resistance to downy mildew in well-known and widely produced hybrids. Except that, Pl-genes were introduced to large number of new inbred lines and new downy mildew resistant hybrids.