The variabihty of seed tocopherol content in wild sunflower species, the expressivity of tph\ and tph2 mutations in different lines and the oxidative stability of sunflower oil with altered tocopherol and fatty acid composition were objectives of this research.Near-isogenic lines for three genes, i.e. Tphl, Tphl, and 01, were developed and investigated. Tocopherol content was determined with TLC and HPLC, as well as fatty acid composition with GC of methyl esters. Rancimat tests were used to estimate the oxidative stability of the oil.The seed tocopherol composition of wild sunflower species was shown to be uniform with a prevailing content ofthe a-homologue (90-99%). The genetic background of different near-isogenic hnes was found to influence expressivity of mutations for tocopherol composition. High content of strong antioxidants, such as ^-, y-, and (5-tocopherols increased oil oxidative stabihty of linoleic and oleic types of oil by 1.2-3.0 times.The breeding model of sunflower hybrids should include antioxidant and vitamin parameters balanced for oils of different applications.

The hexaploid species of Helianthus tuberosus is a potential source of resistance to several sunflower pathogens. But crossed with cultivated sunflower, it produces F, hybrids which have low values of fertility or even full sterility. Pollen viability and meiotic features were studied in 17 populations of the species H. tuberosus and in F1 hybrids. Significant differences in pollen viability existed between populations (47.1–98.8%). In the 15 FI hybrids, plant fertility ranged from 0 to 100 per combination, while pollen viability ranged from 12.4 to 57.1. Meiosis was almost normal in the analyzed species, and irregular in the F, hybrids. The highest percentage of meiocytes was with bivalents (85.9), but univalents (0.3) and multivalents (13.8) occurred as well. In metaphase and anaphase, the percentage of meiocytes with fast and lagging chromosomes was high. In anaphase, chromosome bridges were detected in 9.9 of the meiocytes.

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Oil yield is a major characteristic of each sunflower hybrid (Škorić et al., 2005). To be able to develop new high-oil sunflower hybrids by the method of interspecific hybridization, it is necessary to have information on mode of inheritance and combining abilities of inbred lines used. When selecting prospective lines as components of future hybrids, it is important to know correlations between yield components on one side and oil content on another.Seven new divergent cytoplasmic male sterile lines (A) developed by interspecific hybridization, three Rf-restorer lines used as testers and 21 F 1 hybrids have been subjected to the line × tester analysis. Significant differences have been obtained in mean values for all characteristics under study.Significant differences were found between A lines and R lines on one side and their F 1 hybrids on the other in oil content, plant height, head diameter, total number of seeds per head, 1000-seed weight and seed yield per plant. The line NS-GS-4 exhibited a highly significant positive GCA value for oil content. The line NS-GS-5 had a highly significant negative GCA value for oil content. The hybrid NS-GS-6 × RHA-R-PL-2/1 had a highly significant positive SCA value for oil content. Non-additive component of genetic variance played the main role in the inheritance of oil content, as indicated by the analysis of variance of combining abilities and the analysis of components of genetic variance. Further confirmation was the ratio GCA/SCA for oil content in the F 1 generation which was smaller than unity (0.33). The highest average contribution to the expression of oil content (77.3%) was exhibited by the A lines. Highly significant negative correlations were found between oil content on one side and head diameter, total number of seed per head, 1000-seed weight and seed yield per plant on the other.

The inheritance of the reaction of sunflower to downy mildew was investigated using resistant and susceptible near isogenic lines (NILs) and their F 3 families. Resistance to race 730 was evaluated using the whole seedling inoculation technique. Seventy-three F 3 families were inoculated, among which 54 families were resistant and 19 susceptible, fitting a 3 : 1 segregation ratio. F 3 families were also studied using several PCR markers. Ten markers at the Pl6 locus, specific for the resistant line, also segregated in F 3 families with a 3 : 1 ratio. The same segregation ratio occurred for microsatellite haplotypes that resembled the resistant parent, and were amplified with ORS 166 and ORS 1043. The only common fragment that was observed between resistant and susceptible parental lines was one of the TIR-NBS-LRR resistance gene analogue markers, having a restriction site. Two co-dominant cleaved amplified polymorphic sequence (CAPS) markers were obtained. The mapping data indicate that several dominant markers and two CAPS markers, developed here, completely co-segregate with the Pl6 gene conferring resistance to race 730. CAPS markers will facilitate efficient marker-assisted selection for sunflower resistance to downy mildew race 730.