Determination of the resistance of interspecific and intergeneric sunflower hybrids to orobanche parasitic weed and downy mildew disase and their use in sunflower breeding

In sunflower which is the most important oil seed crop in our country, seed and oil yield are significantly influenced by the parasitic weed broomrape (Orobanche cumana Wallr) and the downy mildew (Plasmopara halstedii) disease. Genetic resistance or high tolerance to these two biotic stres factors are the preferred traits by producers. Wild sunflower species possess many genetic resources resistant to broomrape parasite, which causes significant damage in our country and many cultivation regions World wide, as well as to the downy mildew pathogenraces, under both biotic and abiotic stres conditions. In this study, it is aimed to get benefit from there sistance genetic resources found in wild resources in sunflower breeding programs. Numerous interspecific and intergeneric crosses have been made for this purpose. For this, 7 genotypes of wild sunflower and 4 wild genotypes from the Asteraceae family were used as paternal lines, along with 4 cytoplasmic male sterile (CMS) and 2 maintainer sunflower varieties that are sensitive to broomrape and downy mildew as maternallines. F1 hybrid off spring were obtained by crossing these, and the next year, these hybrids were self-pollinated to obtain F2 generation. Tests for broomrape and downy mildew resistance of the created interspecific and intergeneric hybrids were conducted under laboratory conditions. The broomrape seeds used in inoculation tests were collected using the discovery survey method to represent a wide area in the Thrace region. The pathogenic materials used in disease tests were collected from different locations where downy mildew epidemics were wid espread in theThrace region. In broomrape test evaluations, aggressiveness level (SD) was calculated using the Pustovit method, while in downy mildew tests, resistance was determined based on the ratio of the number of tested plants to the number of diseased plants. In addition, the oil content of the obtained F2 generation was measured by NMR spectrography. Hybrids obtained through self-pollination of interspecific and intergeneric crosses between Carduus acanthoides L. and 3 different IMI-CMS lines resulted in single plants with broomrape resistance and the highest oil content, reaching up to 54%. In the F2 generation of IMI-CMS-2 line×H.annuus, single plants resistant to downy mildew were obtained. In the F2 generation of crosses between Centaurea solstitialis and 2 different IMI-CMS and Cichorium intybus. Maintainer-1, single plants with broomrape resistance (aggressiveness degree: 0) and downy mildew resistance (tested plant count/diseased plant count: 10/0) were identified. In the F2 generation of IMI-069-A, IMI-CMS × IMI-078-A and H.argophyllus crosses, single plants with resistance to broomrape and tolerance to downy mildew, with oil content ranging from 45% to 51.8%, were obtained. In the F2 generation of crosses between sensitive Maintainer-1× H. bolanderi, single plants with an aggressiveness degree of 1 were obtained, but due to insufficient germination in mildew tests, a clear evaluation could not be made. In the F2 generation of IMI-CMS-1×H.graosseserratus and H. atrorubens crosses, single plants with genetic resistance to broomrape and downy milde wwere identified. In the F2 generation of Maintainer-1×H.petiolaris and H.petiolaris subsp. crosses, single plants with Orobanche resistance and mildew tolerance, with the highest oil content of 51.34%, were obtained. When the data obtained in the study are evaluated, it is concluded that there are genes in the F2 generations obtained by self-pollination of hybrids made between sensitive lines and wild species thats how resistance to new strains of broomrape and mildew diseases. The way has been opened for these resistant plants to be used in sunflower resistance breeding programs to create new sources. Additionally, obtaining hybrids with high oil content, which is crucial for sunflower production, can be utilized in developing new sources with elevated oil content.