Backcrosses in interspecific hybridization in sunflower

When incorporating desirable traits (resistance to causal agents of various diseases) from the wild relatives into the cultivated sunflower, some undesirable ones are introduced too (branching, small head diameter, low oil content, etc). To overcome this problem, backcrosses (F1 interspecific hybrids x cultivated sunflower) are used, although very often desirable traits are lost in the process. Cytological analysis (meiosis and pollen viability) and molecular markers (RAPD) were used to estimate what portion of the parental species genome was present in (be interspecific hybrids of the F1 and BC1F1 generations. The results showed that the percentage of irregularities at meiosis increased from F1 to BC1F1 gen. They also indicated the presence of aneuploids and sterility in the cross between the hexaploid species H.rigidus and cultivated sunflower. The genetic distance between the parents was 83%, that between H.rigidus and the F1 hybrid 54 61%, and that between H.annuus and F1 hybrid 70-76%. In the BC1F1 generation, the genetic distance from Hannuus decreased to 58-66% and that from H.rigidus increased to 69-76%

Odnos između heterozisa i genetske udaljenosti određena SSR markerima kod suncokreta (Helianthus annuus L.)

The objective of this study was to determine the correlation between SSR based genetic distance (GD) of new NS sunflower inbred lines and heterosis for six agronomic traits. Twenty three sunflower inbred lines (20 restorer lines and three female lines used as testers) and their hybrids were examined for plant height, head diameter, thousand seed mass, oil content, seed yield per plant and oil yield per plant. Significant heterosis was observed in hybrid combinations for all examined traits except oil content. Genetic distance between pairs of tested sunflower inbred lines ranged from 0.13 to 0.8. There was no significant positive correlation between genetic distance and mid- and better-parent heterosis, specific combining ability and mean value in any of the examined traits for all 60 hybrids. A highly significant negative correlation was found between GD and mean oil percentage (r=-0.33 p lt 0.01). Although GD was generally a poor predictor of heterosis, better results are obtained if hybrid combinations for each tester and each trait are analyzed separately.Cilj rada je utvrdjivanje odnosa između genetske udaljenosti (GD) koja je određena SSR markerima (mikrosatelitima) kod novih inbred linija suncokreta i heterozisa za šest agronomskih svojstava. Ispitano je dvadeset tri inbred linije (dvadeset restorer linija i tri tester linije majki) i njihovi F1 hibridi za sledeća svojstva: visina biljke, prečnik glave, masa 1000 semena, sadržaj ulja u semenu, prinos semena i ulja po biljci. Zapažen je značajan heterozis kod hibridnih kombinacija za sva ispitivana svojstva sem za sadržaj ulja. Genetska udaljenost između parova ispitivanih inbred linija je bila od 0,13 do 0,8. Između genetske udaljenosti i heterozisa, posebnih kombinacionih sposobnosti i srednjih vrednosti svih ispitivanih svojstava, nije bilo značajne pozitivne korelacije. Jedina značajna vrednost, ali negativna, bila je u odnosu srednje vrednosti ulja i genetske udaljenosti (r=- 0.33 p lt 0.01). Iako se genetskom udaljenosti slabo može predvideti heterozis, bolji će se rezultati dobiti ako se analiziraju hibridne kombinacije za svaki tester i svako svojstvo pojedinačno

The use of PCR-based markers in the evaluation of resistance to downy mildew in ns-breeding material

The aim of this work was the application of previously developed and development of new PCR markers for the evaluation of sunflower resistance to downy mildew. Twenty sunflower inbred lines were investigated. Plant resistance to downy mildew was determined by the whole seedling immersion method. Genomic DNA was extracted from the first pair of leaves, and its polymorphism was investigated by RAPD, SSR and several published markers for disease resistance. The presence of the markers Ha-NBS 7/R, Ha-NBS 8/R Ha-NBS 9/R, in Pl6 donor lines (Ha-335, JM-8) and in resistant progeny (Ha-26, G12, G10, G11) confirm that HAP3 could be useful for the detection of the Pl6 gene. DNA polymorphism, which coincided with disease resistance, was revealed with one RAPD (UBC 119 fragment 900-1000 bp) and one SSR primer (ORS37 fragment 600-700 bp). Amplified fragments segregated in the same way i.e., they appeared in 50% of the resistant genotypes. The non-expecting SSR fragment was purified, cloned and sequenced. The results indicated that this fragment is not a part of a coding sequence. Specific primers for the amplification of this fragment have been designed and the investigation of the inheritance of this SCAR marker is under way. None of the applied markers appeared in all resistant genotypes. In order to select lines for making crosses for use in further investigation, the obtained results were also used for the calculation of genetic distances between genotypes (simple matching coefficient) and the construction of a dendrogram (UPGMA method)

Genetic variability of verbascum populations from metal polluted and unpolluted sites

Mullein (Verbascum) plants have extensive distribution and can grow in variable environmental conditions. Seed was collected from mullein plants grown at 4 locations, two metals contaminated and two metal uncontaminated areas. Genetic variability of progeny was examined. Populations collected from unpolluted areas were genetically more similar than those collected from polluted areas as revealed by RAPD and SSR markers and UPGMA analysis. The results indicate that there is genetic differentiation between examined populations and therefore they represent suitable material for further investigation of plant adaptation mechanisms to increased metal content

Using new Rf inbred lines originating from an interspecific population with H. deserticola for development of sunflower hybrids resistant to broomrape

One of the directions in sunflower breeding is the selection for resistance to broomrape. The population of broomrape has been stable in Serbia for a long period of time, but the racial composition has changed in recent years, with race E being predominant in the regions of north Bačka and Banat. Cultivated sunflower is genetically narrow and deficient in many desirable genes. Its genetic variability can be increased by the use of wild sunflower species and interspecific hybridization. The resistance to broomrape in 15 new experimental hybrids was tested on locations in Serbia (Pačir) during three years (2006, 2007 and 2008) and in Romania (Baragan, Braila) during 2008. These hybrids were produced by crossing female inbred lines (Ha-26PR-A, PH-BC2-92-A and Ha-98-A) susceptible to broomrape race E and new Rf inbred lines (RHA-D-2, RHA-D-5, RHA-D- 6, RHA-D-7, RHA-D-8), developed from interspecific populations originating from H. deserticola and resistant to race E. All examined hybrids were resistant to broomrape in both locations. Since broomrape race F is present in the location in Romania, it is expected that the new Rf inbred lines - male components of the examined hybrids, possess the resistance gene for race F also

Effect of morphological and physiological traits on seed yield and oil content in sunflower

Path coefficient analysis was used to separate direct and indirect effects of studied traits on seed oil content and seed yield, and to identify traits that could be used as selection criteria in sunflower breeding. Significant and highly significant correlations were found between most of the examined traits. Highly significant negative correlations have been established between stem diameter, total leaf area per plant, head diameter and 1,000-seed weight on one side and seed oil content on the other. Highly significant positive correlations have been established between seed yield on one side and stem diameter, total leaf area per plant, head diameter, total number of seeds per head, and the 1,000-seed weight on the other. The weight of 1,000 seeds had a highly significant direct negative effect on seed oil content and a highly significant direct positive effect on seed yield. The total number of seeds per head has demonstrated a highly significant direct positive effect on seed yield and oil content. The total leaf number per plant has demonstrated a significant direct positive effect on seed yield. A path coefficient analysis of seed yield at phenotypic level indicated that maximum direct effects were shown by the weight of 1,000 seeds, total number of seeds per head and total leaf number per plant. The total number of seeds per head was the most important trait that determined seed yield and oil content. The obtained results can be used in sunflower breeding programs aimed at the development of sunflower hybrids that combine high genetic potentials for seed yield and seed oil content