Map-based cloning of the restorer gene Rf1, responsible for fertility restoration of the PET1 cytoplasm in sunflower, requires tightly linked markers to the gene of interest. Screening 1200 decamer primers by bulked segregant analyses identified seven RAPD markers mapping on the same linkage group as the restorer gene Rf1. In the F2 population of the cross RHA325(cms) × HA342 (183 individuals) one of the RAPD markers, OPK13_454, mapped 0.9 cM from Rf1, followed by OPY10_740 with 2.2 cM. Bulked segregant analyses using 1024 AFLP primer combinations identified 282 polymorphisms in 203 primer combinations. Selected single plants from the bulks and recombinant plants were screened to further reduce the number of primer combinations to be mapped in the F2 population. The map for the linkage group carrying the restorer gene now consists of 43 markers (7 RAPD-, 1 SSR-, and 35 AFLP-markers) and covers 191.9 cM. E32M36_155 and E44M70_275 were mapped 0.7 cM and 0.1 cM from the restorer gene, respectively. Two of the RAPD markers, OPK13_454 and OPY10_740, were successfully converted into SCAR markers, HRG01 and HRG02, respectively. Amplification of the markers OPK13_454/ HRG01 and OPY10_740/HRG02 was investigated for a set of 11 restorer and nine maintainer lines of PET1. For cloning the restorer gene Rf1, colony hybridizations against high-density BAC filters of our sunflower BAC library and 3D-PCR pooling strategies were used to identify positive BAC clones. BAC fingerprinting using different restriction enzymes in combination with hybridizations was performed to develop a contig around the restorer locus Rf1.

We have developed a segregating mapping population from the cross RHA325(cms) × HA342 comprising 183 F2 individuals. RHA325 is an open American inbred line based on the PET1 cytoplasm while HA342 is a maintainer line for this cytoplasm. The F2 and derived populations segregate for male fertility vs. sterility, downy mildew (Plasmopara halstedii) resistance (Pl2) vs. susceptibility and oleic vs. linoleic acid content. A genetic map was developed covering 1751.5 cM with 202 AFLP and 19 SSR markers in 18 linkage groups. Thirteen linkage groups contain one or more SSR markers and are numbered according to Tang et al. (2002). A segregation ratio of 1 (male fertile, Rf1Rf1) : 2 (male fertile, Rf1rf1):1 (male sterile, rf1rf1) was observed in the F2 population as expected for one seg regating restorer gene (χ2=2.83, P=0.24). In F3, 14 progeny plants of each fer tile F2 individual were evaluated for male fertility to distinguish between F2 plants being homozygous or heterozygous for the restorer gene. The data obtained from the F3 progenies were confirmed by segregation analyses in an F2BC1 population. The Rf1 locus was shown to be located on linkage group 13, containing the SSR markers ORS388 and ORS1030. Using a whole-seedling-immersion test (Gulya et al., 1991) applied to F3 progeny plants we found that the F2 population RHA325(cms) × HA342 segre gated for Plasmopara reaction at a ratio of 1 (Pl2Pl2):2(Pl2pl2):1 (pl2pl2);χ2=0.83 (P=0.65). The Pl2 gene was demonstrated to be located on linkage group 8 together with the SSR marker ORS599. Furthermore, quantitative trait loci for oleic vs. linoleic acid contents (LOD >3) could be localized on linkage group A. Future work will concentrate on marker saturation of the genetic map.

The establishment of an efficient Agrobacterium–mediated transformation protocol for a recalcitrant crop like high oleic sunflower genotypes, cv. Capella and SWSR2 inbred line, is presented in this paper. The protocol requires the identification and optimization of parameters affecting T-DNA delivery and plant regeneration. The basis for identifying the most appropriate conditions for transformation was the fluorometric, histochemical GUS activity coupled with plant cell vitality. Agrobacterium tumefaciens–mediated transformation was performed using strain LBA4404 for cv. Capella and strain GV3101 for the inbred line. Both strains harboring the pBI121 plasmid with the gus gene were under the control of 35S promoter. The flourometric GUS activity was increased in cv. Capella and SWSR2 inbred line 1.9 and 1.6 fold, respectively, relative to transformation without inducers, by optimizing the bacterial density to OD600=1.0, by splitting shoot apices and by using MS medium as a co-cultivation medium supplemented with 200 µM acetosyrin gone. Pre-culturing the explants for three days on SIM2 medium before the bacterial inoculation followed by co-cultivation for 72 h increased the percentage of the GUS expression to 40% and 30% in cv. Capella and SWSR2 inbred line, respectively. It also improved the regeneration percentage as well as the vitality of cells.

The Pervenets mutation raises the oleic acid content (OAC) from about 25% (LO linoleic sunflower) to over 75% (HO sunflower) in sunflower seed oil whatever the genetic backgrounds of the genotypes: fixed mutant lines, hybrid between fixed mutant lines and, surprisingly, both direction cross hybrids between high oleic × linoleic and linoleic × high oleic lines. Here we develop the methodology to point out the coincidence between the mutation and the oleate-desaturase locus. The mutation function is modeled to explain the phenotype. A series of sunflower genotypes developing embryos between 12 and 24 days after pollination without or carrying the Pervenets mutation was used to compare oleate-desaturase transcript accumulation. This revealed the presence and absence of the transcript, in normal LO and Pervenets HO embryos, respectively, whereas stearate-desaturase transcript accumulation was equivalent in both types. The RFLP approach using oleate-desaturase cDNA as a probe has revealed that in comparison with the linoleic sunflower, those carrying Pervenets mutation displayed, besides a common 5.8 kb EcoRI fragment, an extra 8 kb EcoRI fragment and, with HindIII, the shift from 8 kb to 16 kb of a HindIII fragment. The common 5.8 kb EcoRI fragment to Pervenets and nor mal sunflower carries an oleate-desaturase gene. The insertion unique to the sunflower carrying Pervenets mutation has to carry oleate-desaturase sequences. The genetic studies of this mutation have lead to contradictory results in the inheritance pattern of the HO trait due to variable mutation expression and several genetic factors affecting the HO level. Thus, it appeared important to study the inheritance in a set of recombinant inbred lines. Moreo ver, we pointed out that the presence of the mutation is not sufficient to induce the HO phenotype since a suppressor of the mutation “supole” may mask the HO trait. The supole allele is revealed in half of the HO RI lines, and consequently its accurate mapping is difficult. Thus conjunction of the molecular and genetic methods and of material construction was required to solve this problem and to provide efficient tools to breed HO sunflower.

The current trend in human diets is to decrease consumption of the saturated palmitic and stearic fatty acids. Healthy diets restricting not only total fat, but the saturated portion of that fat, would decrease blood serum cholesterol and the risk of coronary heart diseases. Edible vegetable oils are the principal source of fats in many diets. Sunflower oil, which is fifth in production among edible vegetable oils in the world, contains 65 g kg-1 saturated palmitic and 45 g kg-1 saturated stearic acids. These concentrations are high compared to rapeseed oil with 40 g kg-1 palmitic and 20 g kg-1 stearic acids. A reduction of saturated fats in traditional sunflower oil would lead to a healthier edible oil. The objective of this preliminary study was to search the vast genetic diversity avail able from wild Helianthus annuus, the closest relative of the cultivated sun flower, for potential sources of reduced saturated fatty acids; less than 70 g kg 1 combined palmitic and stearic fatty acids. Achenes of eighty-two populations of wild H. annuus were collected from the central Great Plains of the USA. Composited 20-achene samples from each population were analyzed for satu rated fatty acids using organic base-catalyzed transesterification of fatty acid methyl esters and capillary gas chromatography. The average palmitic acid concentration ranged from 39 to 65 g kg-1 for the populations. Average stearic acid concentrations ranged from 19 to 37 g kg-1. Achene oil of one population of wild H. annuus from Holmquist, South Dakota, USA had a palmitic acid concentration averaging 39 g kg-1, while stearic acid averaged 19 g kg-1. The combined 58 g kg-1 palmitic and stearic acids is almost 50% lower than the present level of these fatty acids in sunflower oil. The level of saturated fatty acids observed in the population remained low when plants were grown in the greenhouse under uniform conditions. In the greenhouse, palmitic acid con centration of this population averaged 40 g kg-1, while stearic acid averaged 19 g kg-1. Crosses between this population and an inbred cultivated line produced F1 plants with an achene oil that averaged 39 g kg-1 palmitic and 21 g kg-1 stearic acid. In comparison, the inbred cultivated parent averaged 61 g kg-1 palmitic and 51 g kg-1 stearic acid. F2 plants produced achene oil that aver aged 45 g kg-1 palmitic and 23 g kg-1 stearic acid, for a total of 68 g kg-1. When F1 plants were backcrossed to the cultivated inbred, BC1F1 plants produced an achene oil that averaged 45 g kg-1 palmitic and 26 g kg-1 stearic acid for a total of 71 g kg-1. In comparison, the inbred cultivated parent averaged 65 g kg-1 palmitic and 42 g kg-1 stearic acid, for a total of 107 g kg-1. Preliminary infor mation indicates that palmitic and stearic fatty acids in sunflower oil can be reduced by introducing genes from a wild annual population into cultivated sunflower. Further research will be needed to determine the inheritance of these fatty acids. Other agronomic traits will also have to be monitored during introgression of the fatty acids genes.

The modification of fatty acid composition of two sunflowers inbred lines, HA89 and R978, low oleic acid (normal) and high oleic acid (mutant) respectively, in seeds and during the first stages of growth (A1-B2) was studied under controlled conditions. Enzymatic mechanisms have great effect on the catabolism of seed stored lipids. Temperature and oxygen regulation influence developing sunflower seeds. For simultaneous study of seed and developing seed, half-seed analysis technique was used. The behavior of the fatty acids during the germination in cotyledon of seed showed the increase of linolenic acid in both lines, demonstrating the activity of linoleic acid desaturase (∆6-desatu rase). But linoleic acid as a substrate for linoleate desaturase increased during all stages of developing only in mutant line that revealed higher activity of oleic acid desaturase (∆12-desaturase) in transforming oleic acid to linoleic acid in this line, and lower activity of this enzyme in low oleic acid line, the reasons probably being the low availability of substrate of this enzyme in low oleic acid line and the complexity of enzymatic mechanisms. The modification of fatty acids in developing sunflower, depends not only on ambient conditions such as temperature and oxygen regulation as described by many authors, but also on the genotype.

Environmental factors, mainly temperature and water availability, play a major role with genotype factor in oil quality of sunflower. To manage seed composition through cultural practices and genotype choice under scarce water resources is one way to provide an added-value to crop yield and to diversify uses for edible oil or for non food applications in Mediterranean regions. The study of interactions between crop management and genotypes for yield and also for major seed compounds (oil, protein and fatty acids) was conducted in the Rotation-Quality device in Toulouse-Auzeville (France) during three experimental years. Two standard populations and four hybrids (two oleic and two standard), well adapted to cropping systems in Morocco and France, were investigated in conventional and late sowing dates associated with non-irrigated and irrigated treatments. For all genotypes, delay of sowing improves protein content and seed weight but decreases yield, stronger for populations compared with hybrids whereas oil content is not depressed. Globally, in irrigated crop, only the percentage of protein in seed dry matter decreases. The oleic and linoleic acids contents in standard hybrids seeds are sensitive to sowing date whereas oleic hybrids and populations' contents are relatively more stable. Indeed, oleic acid content in standard hybrid seeds increases with a concomitant reduction of linoleic acid content in the case of late sowing. Water regime does not affect the oleic and linoleic acids. The delay in sowing decreases stearic and palmitic acid contents in oleic hybrid seeds, and in standard hybrid seeds only palmitic acid content. These saturated fatty acids contents are not affected by irrigation treatment. Close negative correlations between oleic and linoleic acids and between oleic and palmitic acids are present in all genotypes and treatments. Our results suggest that there exist different genotype behaviors for fatty acids accumulation in response to crop management.

Tocopherols are the main compounds with antioxidant activity in oilseeds. Sunflower seeds contain predominantly alpha-tocopherol, which accounts for more than 90% of the total tocopherols in the seeds. This tocopherol derivative possesses a maximum vitamin E or in vivo antioxidant activity, but it exerts a minimum in vitro protective action in oils and food containing them. Other tocopherol derivatives such as beta-, gamma-, and delta-tocopherol are more powerful antioxidants than alpha-tocopherol. Accordingly, a partial replacement of alpha-tocopherol in sunflower seeds is an important breeding objective. So far, variants with high gamma tocopherol content (>85%), medium beta-tocopherol content (30% to 50%), and medium delta-tocopherol content (<25%) have been developed. The objective of the present research was to develop sunflower germplasm with novel tocopherol profiles. Seed of four Peredovik accessions of different origins were used for chemical mutagenesis with ethyl methane sulfonate (EMS). Single-seed screen ing in the M2 generation resulted in the identification of an M2 seed with 19% gamma-tocopherol. M3 seeds exhibited wide segregation for gamma-tocopherol content, from zero to about 85%. Such a wide segregation has not been observed in previously developed high gamma-tocopherol germplasms, which segregate for low and high but not for intermediate levels of gamma-tocopherol. Selection for high gamma-tocopherol content within this mutant produced an M4:5 line with stable high concentration of gamma-tocopherol, above 90% of the total tocopherols. The line was designated IAST-1. Crosses between IAST-1 and the line T589, with medium beta-tocopherol content, produced segregants with increased levels of up to 68% delta-tocopherol.

Wild Helianthus species are an important reservoir of useful genes for sunflower breeding. The objective of the present research was to evaluate the existing variability for tocopherol content and composition in a germplasm collection of wild sunflower species. The germplasm evaluated consisted of 257 accessions from 36 Helianthus species, including both annual and perennial species. Eight seeds per accession were randomly picked and bulked for tocopherol analysis conducted by HPLC with fluorescence detection. Tocopherol content averaged 328 mg kg-1 seed in the analyzed accessions, with an average profile of 99.0% alpha-tocopherol, 0.7% beta-tocopherol, and 0.3% gamma tocopherol. In cultivated material, an average tocopherol content of 669.1 mg kg-1 seed have been reported, made up of 92.4% alpha-tocopherol, 5.6% beta tocopherol, and 2.0% gamma-tocopherol. The maximum total tocopherol con tent in wild sunflower germplasm corresponded to an accession of H. maximilianii, with 673 mg kg-1 seed. Increased levels of beta-tocopherol were identified in one accession of H. praecox (11.2% of the total tocopherols) and one acces sion of H. debilis (11.8%). All other accessions contained less than 6.5% beta tocopherol. Increased gamma-tocopherol levels were identified in one accession of H. exilis (7.4%) and two accessions of H. nutalii (11.0% and 14.6%, respectively). All other accessions contained less than 2% gamma-tocopherol. Although further research at an intrapopulation level is needed to confirm and isolate variants, the results of the present research indicated that wild Helianthus germplasm contains useful variability for tocopherol content and composition.

Two new inbred lines, T589 (medium β-tocopherol content) and T2100 (high γ-tocopherol content), recently developed in CSIC, Cordoba, Spain, have been crossed to known tph1 and tph2 mutations which possessed the same phenotypes and which were obtained at VNIIMK, Krasnodar, Russia. Genetic identification of these recessive mutations with TLC profiles showed the new medium β-tocopherol mutation to be allelic to tph1 and the new high γ-toco pherol mutation to be allelic to tph2.

In this paper we show the seed characteristics and oil and protein quality parameters used at Veidelevka Institute of Sunflower (VIS) for obtaining the original sunflower material. As a result of the breeding program, a donor of super high oil percentage was selected that has no negative influence on economically valuable characteristics.

A comparison of H. argophyllus and H. debilis ssp. cucumerifolius populations from the coast of Mozambique and Eastern South Africa and Texas, USA was carried out at Udine University (Italy). American populations were supplied by the USDA Northern Crop Science Lab, while the populations from Africa were collected over several years by Udine researchers. Populations comparison were based on morphological traits and nuclear and chloroplastic SSR markers of plants grown in pots in a growth chamber. All populations are of potential interest to breeding programs as well as for evolutionary studies. Hybrid populations involved both species and for some African swarms possibly H. annuus. For H. argophyllus, there is evidence of a bottleneck effect. Material coming from Texas showed a lower number of alleles in nuclear SSR compared with the African material.

Two wild Helianthus species native to North America have been natural ized in Argentina, H. annuus ssp. annuus and H. petiolaris. They grow as adventitious overlapping about 50% of the crop area. Hybridization and introgression between these wild species and sunflower have important biological and practical consequences, the former including homoploid hybrid species formation, and the latter including a possibility of transgene spreading from genetically modified (GM) sunflower cultivars to wild or weedy populations. Wild populations were screened for isozyme and morphological variation. Intermediate plants were found in several locations and subjected to progeny tests. Variability among progeny of each one was compared with the variability in wild accessions of both species. Segregation for phenotypic traits, intermediate phenology and low fertility levels were found in most progenies, accounting for the hybrid origin of their maternal plants. Attempts to quantify gene flow included screening of progenies from H. petiolaris populations growing near sunflower crops. Hybrid plants were recognized by morphological traits and reduced fertility. Overall hybridization was about 1%. Hybrid progeny on wild H. annuus plants were identified by a crop isozyme marker. A mean frequency of 7% hybridization was found. These results confirm that gene flow occurs among crop and wild Helianthus species, and it concerns crop management and environmental impact if release of GM sunflower cultivars is to be authorized in Argentina.

The paper described the features of wild sunflower species that are used to develop original material possessing economically valuable and breeding characteristics.

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 ampli fication of this fragment have been designed and the investigation of the inher itance 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).

The inbred line R28, coming from Helianthus argophyllus, displays low susceptibility to both artificial and natural infection by basal stem and head rot and to artificial infection by fungus filtrate (oxalic acid). A cross was made between this line and 9304 (a susceptible inbred line). F2 plants, parental plants and F1 plants, were artificially infected by: i. pathogen mycelium over the basal stem (basal stem attack), ii. ascospores on the head (head rot attack). As result of basal stem infection, 72.4% of the F2 plants showed symptoms and died. Incubation period (IP), as the number of days from infection to the appearance of first symptoms, varied from 5 to 25 days, with a population mean of 12.5±6.1 days. The IPs in 9304, F1 and R 28 were 7, 10 and 16 days, respectively. The same IP character and the percentages of lesions on the capitulum, monitored at the end of flowering time (EF) and at physiological maturity (PM), were also measured after the infection with ascospores. After the ascospore test, 60.7% of the infected F2 plants showed disease symptoms on the capitu lum. In this case the IP ranged between 16 and 45 days, with a population mean of 27.6 ± 6.4 days. The IPs for 9304, F1 and R 28 were 18, 25 and 35 days, respectively. Among all the plants with lesions at PM, 24% was completely safe at EF, thus showing different reactions of F2 genotypes against Sclerotinia. Relationship among EF, PM and IP were investigated and the obtained results suggest two different Sclerotinia attack mechanisms. This paper discusses the possibility of obtaining some results from classi cal selection programs utilizing these parameters. We are also considering a molecular markers assisted approach. Recently, several hundred microsatellite markers were developed for sunflower. For this purpose we have selected a first set of primer combinations on the basis of amplicon length to facilitate multiplexing. SSR markers were screened for polymorphism using three-color multiplexes.

Sunflower head rot (SHR) (Sclerotinia sclerotiorum (Lib.) de Bary) is one of the major diseases affecting this crop worldwide. In spite of reports of different levels of susceptibility among sunflower genotypes, there is no evidence of complete resistance in any commercial hybrid. The aim of this work was to evaluate the number of infection courts and the length of the susceptible period in two genotypes with contrasting but stable SHR susceptibility. Repeated experiments during three years in the field included the sunflower hybrids Paraíso-20, moderately resistant, and Rancul, susceptible. Plants were inoculated with ascospores by spray application. Only one or two infection courts were found in each infected sunflower head and this feature did not distinguish cultivar susceptibility. Differences between cultivars were detected considering the length of the susceptible period based on disease incidence higher than zero (LSP) or higher than 10% (LSP10) in two out of three years. LSP was longer in Rancul (28 days) than in Paraíso-20 (17 days). Also LSP10 was longer in Rancul (22 days) than in Paraíso-20 (9 days). The suitability of these two features as components of partial resistance is discussed.

The holoparasitic angiosperm sunflower broomrape (Orobanche cumana Wallr.) is currently regarded as one of the most important constraints of sunflower production in many areas in Southern Europe and the Black Sea region. Breeding for resistance is considered to be the most effective and feasible method of controlling sunflower broomrape. Commercial hybrids cultivated in Spain carry the Or1 to Or5 genes that confer resistance to races A to E. However, a new race, designated F, has been identified. Germplasm with race F resistant genes derived from wild and cultivated sunflowers has been developed. Dominance reaction of these genes is an essential feature that determine the breeding method to produce race F resistant sunflower hybrids. Crosses between different sources of race F resistant lines, including those derived from wild and cultivated sunflower, and different susceptible parental lines were made. Allelic crosses between race F resistant lines, as well as crosses between race F resistant lines and race E resistant lines were also carried out. F1 plants, F2 plants, and their parental lines were evaluated for their disease reaction to race F or race E of broomrape. Different dominance reactions and inheritance mechanisms for broomrape resistance were observed. These depended on the race of broomrape, the source of race F resistance, and also the susceptible parental line used for the cross. The relevance of the results obtained for sunflower breeding for resistance to sunflower broomrape is discussed.

Broomrape (Orobanche cumana Wallr.) is a parasitic plant that feeds on sunflower roots. In recent years, a new, aggressive race designated as race F (called biotype D in Russia) has spread drastically in Spain. The aim of our work was to find donors of resistance to this biotype, to study heredity of this trait and to develop new sunflower inbred lines combining F-race broomrape resistance with other valuable traits. Preliminary resistance tests showed that practically all VNIIMK-released and prospective inbred lines are susceptible to the new broomrape race, with only VK-623 exhibiting resistance. Conse quently, we tested all breeding materials obtained from VK-623 as a parental line as well as all F1 hybrids. All F1 hybrids were susceptible to the new race, indicating that the resistance was recessive. Among the tested breeding material, resistant plants were encountered with different rates. Fifteen resistant plants were found in the progeny of two F3 morphologically different plants from a hybrid combination 14B × (VK-623 × VK-616). After testing, all of them were transplanted and self-pollinated. Their progeny proved their resistance in the next year tests. As a result, two new prospective inbred sunflower lines were developed, which exhibited resistance to broomrape races C and D. However, as the recessive character of the obtained resistance creates some difficulties in commercial sunflower hybrid breeding, we shall continue to look for new dominant resistance genes donors among the sunflower samples.

New broomrape races threaten sunflower production in Turkey. Pioneer hybrid P-4223 was resistant in all parts but TARSAN-1018 and some inbred lines were resistant only in some areas in Trakya region. At least one or more new races than F race appear to exist in the region. Use of imidazolinone herbicide and resistant hybrid started in 2003. Farmers used this Clearfield System® without any problem. This system will be preferred in coming years by farmers in areas problematic for broomrape and weeds, for use together with sunflower cultivars genetically resistant to broomrape.

New broomrape races have spread quickly year after year to reach 70% of the sunflower acreage in Trakya region of Turkey. These new races were more virulent in Turkey than in other countries such as Spain and at least one more race other than F race was observed in Trakya. Some inbred lines from Trakya Agricultural Research Institute-Edirne (TARI) exhibited resistance in some parts of the region, but the sunflower hybrid PR-64-A-95 exhibited resistance in all locations. This hybrid and other resistant lines will be evaluated again in subsequent years and they will be used as a differential set for determining new broomrape races.

The sunflower is susceptible to a large number of pathogens. Facultative fungal parasites are most harmful to sunflower yield. In this paper we have summarized the results of immunological research on the original and breeding material of sunflower carried out at Veidelevka Institute of Sunflower in recent years. Data on the efficiency of different disinfectants are also presented here.

In this research, we investigated the response of sunflower cultivars to drought stress under both in vitro and in vivo conditions. Murashige and Skoog basal medium supplemented with a range of polyethylene glycol (PEG-1000) concentrations was used for in vitro drought screening. Results from both in vitro and in vitro experiments showed that plant growth decreased with increasing PEG concentrations. In addition, there were differences between the cultivars in terms of their response to drought. The significant correlations between in vitro (except number of roots) and in vivo characters indicate that an in vitro approach could be useful in screening and selecting for drought response prior to field trial. As a result, all in vitro characters measured (except number of roots) could give clues for performance of sunflower genotypes against drought in vivo.

In vitro culture has become a useful tool for studies concerning the assessment of physiological and biochemical factors controlling floral morphogenesis. For sunflower, in vitro techniques starting from different explants yield good results on culture initiation and plant regeneration. Although inflorescence generation on cultured shoots is sometimes achieved, there are no reports about in vitro florets developed from cultured young capitula. This work describes a protocol for the in vitro culture of sunflower reproductive meristems where floral organogenesis can be expressed. Experiments were carried out using undifferentiated sunflower capitula excised from plants grown under greenhouse conditions. White (W) and Linsmaier and Skoog (LS) culture media were compared. LS medium induced a comparatively large capitula receptacle area expansion, reduced the explant hyperhydration and calli formation and was chosen for further experiments. The presence of casein hydrolysate (CH) in LS culture media was tested, result ing in reduced surgical stress and recovery of explants. The addition of Kinetin to LS medium plus CH proved to induce differentiation of new primordia at the capitulum generative front. Explants cultured with 0.1 mg l-1 Kinetin only differentiated mother bract primordia. Explants cultured with 1 mg l-1 Kinetin showed larger expansion of the receptacle area and new floret primordia did not differentiate their mother bract. Intermediate levels of kinetin (0.5 and 0.8 mg l-1) were tested in addition to two levels of IAA (1.3 and 2.5 mg l-1). The combination 0.8 mg l-1 Kinetin and 2.5 mg l-1 IAA was capable of differentiating floret primordia that closely resembled those formed in the capitula developed in vivo.

Thirteen new sterile cms analogues on the base of different sunflower cms sources have been obtained. The obtained backcrosses have been evaluated for main agronomic traits, including the resistance to the important sunflower pathogens. As a result of this study, the most prospective cms analogues were designated for future use in breeding programs.

Twelve commercial sunflower hybrids were evaluated as possible standards for classifying sunflower hybrids into maturity groups at the different growth stages of sunflower for maturity classification of new hybrids in the U.S. Due to the narrow range among hybrids only four maturity classes were determined. Hybrids earlier than NK 231 were classified as the earliest group, between NK 231 and D-3868 as the second maturity group, between D-3868 and C-187 as the third group and hybrids later than C-187 as the latest maturity group. This grouping system was based on mean separation procedures using LSD values, and lowest MSEs. For detailed evaluation of physiological maturity, H-311 and K-8806 could be used as additional standards of very early and very late hybrids to give six maturity groups.