Wild Sunflower Species Research Articles

Alberta Regional Meeting, 2005, The Canadian Phytopathological Society / Réunion régionale de l’Alberta, 2005, La Société canadienne de phytopathologie

Alberta Regional Meeting, 2005, The Canadian Phytopathological Society / Réunion régionale de l’Alberta, 2005, La Société canadienne de phytopathologie

Regeneration of interspecific somatic hybrids between Helianthus annuus L. and Helianthus maximiliani (Schrader) via protoplast electrofusion

Helianthus maximiliani is one of the wild Helianthus species with the genes for resistance to many pathogens including Sclerotinia sclerotiorum. Unfortunately, a transfer of disease resistance genes from this species into the cultivated sunflower is limited by its poor crossability with the cultivated sunflower and sterility of interspecific hybrids. To overcome this problem, mesophyll protoplasts of Sclerotinia sclerotiorum-resistant clone of H. maximiliani were electrically fused with etiolated hypocotyl protoplasts of the cultivated sunflower inbred line PH-BC1-91A. Fusion products were embedded in agarose droplets and subjected to different regeneration protocols. Developed microcalluses were released from the agarose and transferred into solid media. Shoot regeneration was achieved by culture of calluses on regeneration medium containing 2.2 mg l(-1) BAP and 0.01 mg l(-1) NAA after the treatment with a high concentration of 2,4 D for a limited period of time. A morphological and RAPD analysis confirmed a hybrid nature of the regenerated plants.

Wild helianthus species used for broadening the genetic base of cultivated sunflower in India

SUMMARY The present investigation has been undertaken to introgress desirable traits from wild sunflowers to cultivated sunflower. Using conventional methods of crossing, backcrossing and selection, several pre-bred lines with altered plant architecture, high yield and oil content, maturity duration and inbuilt tolerance to major biotic stresses have been developed from crosses involving diploid annuals. These recombinant interspecific inbred lines are being utilized in the national sunflower network program for development of inbred lines and heterosis breeding. The pre-bred lines were characterized through cytological and molecular techniques using sunflower specific SSRs. Diploid perennial and hexaploid species have been utilized in the program aimed at introgression of resistance to A. helianthi through various ploidy manipulation procedures. The utility of the prebreeding material in the sunflower network program in India is presented. RESUMEN Esta investigación fue emprendida con el fin de realizar el traspaso de las características favorables de las especies silvestres en el girasol cultivado. Utilizando los métodos de cruzamiento estándares, el cruzamiento reversible y la selección, varias líneas de preselección con la arquitectura alterada y período de vegetación de la planta, el alto rendimiento contenido de aceite y la tolerancia hacia los estreses bióticos principales agregada, han sido engendradas por cruzamientos, que incluían las especies diploides anuales. Esas líneas interespecies consanguíneas recombinantes se utilizan en la red nacional para la investigación de girasol para la formación de las líneas consanguíneas y selección heterotrófica. Las líneas de preselección se caracterizan por las técnicas citológicas y moleculares sobre la base de los marcadores específicos SSRs. Las especies diploides y hexaploides perennes son utilizadas en el programa de introducción de la resistencia hacia A. helianthi mediante diferentes métodos de manipulación con los niveles de ploidía. En el trabajo se demuestra el grado de utilización del material de preselección en los programas de selección de girasol en India. RÉSUMÉ Cette recherche a été entreprise dans le but d’intégrer des caractéristiques du tournesol sauvage au tournesol de culture. En utilisant les méthodes courantes de croisement, de rétrocroisement et de sélection, on a développé plusieurs lignées présélectionnées avec architecture végétale et durée de végétation altérées, rendement et contenu d’huile élevés et tolérance au principaux stress biotiques à partir de croisements incluant des espèces diploïdes annuelles. On utilise ces lignées autogames interspécifiques recombinantes dans le programme du tournesol du réseau national pour développer des lignes autogames et pour la sélection hétérosis. Les lignées présélectionnées ont été caractérisées par les techniques cytologiques et moléculaires utilisant des marqueurs spécifiques SSRs. Les vivaces diploïdes et hexaploïdes ont été utilisées dans un programme destiné à l’intégration d’une résistance à l’ A. helianthi par différents procédés de manipulation au niveau de la ploïdie. L’article présente l’utilité du matériel présélectionné dans le programme de sélection du tournesol en Inde.

Identification of wild species of sunflower by a specific plastid DNA sequence

SUMMARY Four sunflower species, Helianthus annuus , H. argophyllus , H. debilis and H. tuberosus , were characterized at the molecular level using the plastid trnH-psbA intergenic spacer. The trnH-psbA sequence was selected with the aim of developing a “DNA barcode” system (Kress et al. , 2005) as a tool for species and specimen identification. The plastid region was PCR amplified with specific primers and sequenced with an ABI Prism 3730 Automated DNA sequencer. Intraspecific and interspecific sequence variation was evaluated to assess the resolution of the technique. Sequencing of both forward and reverse strands allowed for a high base calling accuracy and overcame the problem of polymerase slippage within microsatellite regions. After sequence editing, a very low (or absent) intraspecific variability was detected, whereas interspecific variability due to SNPs, indels and SSR length was sufficient for an unambiguous identification of each species. RESUMEN Fue hecha la caracterización de cuatro especies de girasol, Helianthus annuus , H. argophyllus , H. debilis y H. tuberosus , a nivel molecular, por la técnica ’plastid trnH-psbA intergenic spacer’. La secuencia trnH-psbA fue elegida con el objetivo de crear el sistema de “código de barras DNA” (Kress et al. , 2005), que serviría como herramienta para la identificación de las especies vegetales y muestras. La región plastidial está fortificada con la técnica PCR junto con la utilización de los “primers” específicos y secuencionado en el secuenciador automático de DNA “ABI Prism 3730”. La calificación de variabilidad de las secuencias de intra- e interespecies fue realizada con el fin de calificar la precisión de la técnica utilizada. El secuencionamiento de las partes de DNA en las dos direcciones, fue satisfactoriamente exacto, y fue superado el problema de distorsión de la imagen dentro de las regiones microsatélites. Tras la ordenación de las secuencias, la determinada variabilidad de interespecies era baja o no existía. La variabilidad de interespecies SNP, de los fragmentos indel y de longitud de los fragmentos SSR, era suficiente para la identificación irrebatible de cada especie por separado. RÉSUMÉ Les quatre espèces de tournesol, Helianthus annuus , H. argophyllus , H. debilis et H. tuberosus ont été caractérisées au niveau moléculaire par l’espaceur intergénique plastide trnH-psbA. La séquence trnH-psbA a été choisie dans le but de développer un système de „code-barres ADN“ (Kress et al. , 2005) comme outil d’identification d’espèces et d’échantillons. La région plastide a été amplifiée par la méthode PCR avec des amorces spécifiques et séquencée avec un séquenceur ADN automatique “ABI prisme 3730”. La variation de séquence intra et interspécifique a été évaluée pour déterminer la précision de la technique utilisée. Le séquençage des parties d’ADN dans les deux directions a été suffisamment exact et le problème de dérapage polymérase à l’intérieur des régions microsatellites a été maîtrisé. Après organisation de la séquence, une variabilité interspécifique faible ou inexistante a été détectée tandis que la variabilité interspécifique due aux SNP, indels et longueur de SSR suffisait à identifier sans ambiguïté chaque espèce.

Exploration for wild Helianthus species from the desert Southwestern USA for potential drought tolerance

The ability of some sunflower species to survive and thrive in shifting sand dunes with an annual precipitation of 50 mm could be of value for cultivated sunflower, a crop often grown in arid regions. The genus Helianthus comprises 51 species and 19 subspecies, with 14 annual and 37 perennial species, all native to North America. The objective of this study was to collect achenes from as many populations as possible of desert species, specifically annual H. anomalus, H. deserticola, H. niveus ssp. canescens, and perennial H. niveus ssp. tephrodes from the desert southwestern USA and make them available for future research and improvement of cultivated sunflower. The first exploration for H. anomalus and H. deserticola took place from September 16 to 23, 2000, covering 4100 km in three states, Utah, Arizona, and Nevada; while the second exploration concentrated on H. deserticola populations in west central Nevada, taking place between June 20 to 23 and August 15 to 18, 2005. The third exploration for H. niveus ssp. tephrodes took place from February 26 through March 5, 2005, covering 2200 km in southern California and adjacent Arizona. Only one population of H. deserticola from Utah and two populations of H. anomalus from Utah were collected in 2000. The 2005 exploration in Nevada resulted in the collection of achenes from 13 populations of H. deserticola. In 2005, five populations of H. niveus ssp. tephrodes were collected from the Alogodones Dunes in California. One population of H. niveus ssp. canescens was collected from Yuma, Arizona, near the US-Mexico border, with three additional populations collected from the Pinta Sands area of Arizona, which is the northernmost extension of the Gran Desierto of Sonora, Mexico. Achene samples of each collection are maintained and distributed from the USDA-ARS National Plant Germplasm System, North Central Regional Plant Introduction Station, Ames, Iowa. The limited number of desert species populations collected will provide basic germplasm for further research dealing with improving drought tolerance in cultivated sunflower. .

The wild sunflowers collection in Novi Sad

Lowered genetic variability in the cultivated sunflower and use of interspecies hybridization in sunflower breeding were the main reasons to establish the wild species collection. Wild species were collected during collecting trips performed jointly by researchers from Novi Sad and Fargo from 1980 to 1991. A total of 917 accessions were gathered. Different numbers of species (1-37) and populations (52-384) were gathered in each trip and wild sunflower habitats were inspected in 6-21 US federal states. Presently, there are 21 perennial and 7 annual species in the collection, represented by 447 accessions. The perennial species are grown in quarantine fields (311 accessions) and kept in temporary seed storage at +4° (163 accessions). Annual species are sawn each year and 136 accessions are kept in temporary seed storage. Seed reserves vary from a few seeds to several thousand per accession and all of them were produced in the period between 1998 and 2004. Several problems were encountered in the course of the establishment, maintenance and utilization of the collection: 1. Occasional errors in species determination during collection trips were caused by the presence of natural hybrids, heterogeneity of natural populations and differences in ploidy within the same species; 2. The local continental climate caused loss in material due to winterkill and inability of some species to complete the vegetative cycle; 3. Perennial species were difficult to grow because of low seed viability; 4. Low self-fertility or complete selfsterility precluded seed production and renewal of seed reserves; 5. Wild species were difficult to utilize as a source of desirable genes because of their cross incompatibility with cultivated sunflower.The collection of wild sunflower species has mostly been used for development of disease resistant or tolerant genotypes, new cms and Rf genes and for breeding of special-purpose hybrids.

Variability of Sclerotinia responses in Helianthus petiolaris

SUMMARY Cultivated sunflower ( Helianthus annuus L.) is susceptible to Sclerotinia sclerotiorum (Lib.) de Bary . H. petiolaris Nutt is a wild sunflower species naturalized in Argentina. The objective of this work was to evaluate the responses of some accessions of H. petiolaris to S. sclerotiorum inoculation in order to detect potential sources of resistance to be used in cultivated sunflower. An experiment was carried out at the UIB’s experiment field. Inoculations were made on leaves and stems. Lesion mean on leaves was 22 mm and 24 mm on stems. The accession GRR-252 showed mean lesions on leaves significantly longer than in GRR-250. However, there were no differences for stem inoculation. Correlation analysis indicated the independence of leaf and stem responses. Results obtained after the first experimental trial suggest the possibility of detecting some H. petiolaris accessions with a higher level of resistance to S. sclerotiorum than others. RESUMEN El girasol cultivado ( Helianthus annuus ) es susceptible a las infecciones de Sclerotinia sclerotiorum y la especie silvestre H. petiolaris está naturalizada en la Argentina. El objetivo de este trabajo fue evaluar algunas introducciones de H. petiolaris , mediante inoculaciones de S. sclerotiorum , a fin de detectar potenciales fuentes de resistencia que puedan ser utilizables en el girasol cultivado. Se realizó un experimento en el campo experimental de la UIB. Las inoculaciones se realizaron en hojas y tallos de plantas elegidas adrede. Se obtuvo un promedio de lesión por parcela. La lesión media en hojas fue de 22 mm, mientras que en tallos fue 24 mm. En las hojas, fue posible diferenciar a las introducciones por su comportamiento medio. El valor del test LSD determinó que la lesión promedio de la introducción GRR-252 fue significativamente mayor que la de GRR-250. Para la infección en tallos no hubo diferencias. El coeficiente de correlación de rangos entre las lesiones producidas en cada órgano no fue significativo. Este primer año de resultados indicaría la posibilidad de detectar introducciones con comportamientos diferenciales a S. sclerotiorum . RÉSUMÉ Le tournesol cultivé ( Helianthus annuus ) est sensible au Sclerotinia sclerotiorum. L’ H. petiolaris est une des espèces sauvages de tournesol qui est naturalisée en Argentine. L'objectif de ce travail est d’évaluer quelques introductions d’ H. petiolaris , face aux infections de S. sclerotiorum , afin de détecter des sources de résistance potentielle pour le tournesol cultivé. Une expérience a été mise en place dans l'UIB. Les infections ont été faites en feuilles ainsi qu’en tiges des plantes de H. petiolaris . La moyenne des réponses en feuilles était 22 millimètres, tandis qu’aux tiges était 24 millimètres. En feuilles, des différences significatives ont été détectées parmi les introductions et la valeur de la plus petite différence significative a déterminé que l'introduction GRR- 252 avait un niveau de résistance significativement plus bas que GRR-250. En tiges il n'y a cependant aucune différence parmi les génotypes. Le coefficient de corrélation des rangs parmi les réponses feuilles-tiges n'était non plus significatif. Cette première année des résultats indiquerait la possibilité de détecter des génotypes d’ H. petiolaris de bon comportement face au S. sclerotiorum .

Phenotype variability and inheritance of plant height and branching in f1 generation of sunflower

Highly variable populations of wild sunflower species were crossed with CMS cultivated lines. Variability was determined by measuring plant height and evaluating the type of branching. Mode of inheritance was tested by comparing the 27 hybrid populations against parents. Differences among parents in the observed traits were significant. All modes of inheritance for plant height were present in the F1 generation. Heterosis was most frequent, followed in decreasing order by partial dominance, dominance and intermediacy. More than one mode of inheritance for plant height occurred because of the large variability in wild species and poligenic inheritance of the characteristic. All F1 populations were fully branched, with or without the central head. The wild type of branching was found in F1 because the wild parent dominated in genetic control of that trait over the cultivated one.

The effect of UV light on division capacity of Helianthus mollisL. protoplasts

Cultivated sunflower (Helianthus annuus L.), together with soybean, oil seed rape and peanut is one of the four most important crops for oil production and has a cultivated area that range from Russia, Eastern and Central Europe to Central America. Wild sunflower species served as genetic base for the modern sunflower. Cultivated sunflower was selected from a very narrow genetic base. Enlarging the genetic base will allow it to be better adapted to environmental conditions. Many wild species are used to introduce useful traits, such as disease resistance (Phomopsis stem cancer, Sclerotinia wilt), cytoplasmic male sterility and increased oil content to the cultivated crop by introgression. Sexual hybridisation is limited in most cases to cultivars within a species or at best to a few wild species closely related to a cultivated crop. Species barrier thereby limits the genetic improvement by classic breeding. Somatic hybridisation, or somatic cell fusion technique, leading to the formation of viable cell hybrids is one of the methods used to overcome sexual incompatibility. In order to eliminate the unfavourable wild species traits in the somatic hybrids, a number of back crossings to the cultivated sunflower would be necessary. A method to reduce the backcrossings by reducing the amount of DNA from wild species in the hybrids, is the asymmetric fusion of the protoplasts. This technique is used to introduce fragments of the nuclear genome from the wild species into the complete genome of cultivated ones. A fragmentation of the donor genome can be induced by UV irradiation of the donor protoplasts prior to protoplast fusion. The effect of UV-light treatment was determined on the basis of Helianthus mollis protoplast viability and division capacity. The isolation and purificartion of protoplasts was according to Krasnyanski and Menczel [1] protocol. The suspension of purified protoplasts was placed under a UV lamp during 60 min (wavelength of UV irradiation was 254 nm). Irradiation intensity was 2 Mmol m-2 s-1. Protoplast viability was determined every 5 min, on 100 protoplasts, using FDA, under fluorescent microscope. The protoplasts were cultured in agarose droplets in VKM media. Plating efficiency (the number of cells dividing of total number of cells) was determined at 4 and 8 days in culture. We observed the UV irradiation affects both, viability and division capacity of H. mollis protoplasts. Efficiency of UV-light treatment depends on its intensity and duration, a treatment in our conditions of more than 10 min decreases significantly the viability of the tested cells.

Culture characteristics and histological changes in leaf tissues of cultivated and wild sunflowers infected with Alternaria helianthi

The cultural characteristics and histochemical variations following infection with Alternaria helianthi was studied In six wild Helianthus species of threeploidy levels (diploid, tetraploid and hexaploid) possessing different degrees of resistance to the pathogen and in cultivated sunflower (H. annuus cv. CO-4. susceptible check). Of these, the species II. occidentals and H. tuberosus were found to be highly resistant while H. hlrsutus was moderately resistant. Media supplemented with leaf extracts of wild species, with the exception of H. grosseserratus, supported less growth and sporulation of A. helianthi than media supplemented with leaf extract of cultivated sunflower. Reduced infectivity of the pathogen was recorded when grown on leaf extract media of H. occidentalis, H. hirsutus and H. tuberosus. Furthermore, abnormalities in the shape of conidia were noticed on supplemented media with leaf extracts of H. occidentalis and H. tuberosus. RAPD analysis of the fungal DNA isolated from die pathogen grown on leaf extract media of cultivated and wild Helianthus species revealed no polymorphism. Histochemical studies showed restriction of the pathogen to epidermal cells in resistant wild sunflowers as well as an increased accumulation of phenols.

Biochemical characterization of resistance against Alternaria helianthi in cultivated and wild sunflowers

The biochemical basis of resistance to the leaf spot/blight pathogen A. helianthi was compared in six wild Helianthus species, possessing three ploidy levels (dlploid, telrapiold and hexaplotd) and different degrees of resistance to helianthi, and cultivated sunflower (H. annuus cv. CO-4 susceptible check) in terms of sugar, phenols and isozymes of peroxidase. polyhenol oxidase and chitinase. The resistant species of wild sunflowers (H. tuberosus. H. occidentalis) possessed higher levels of constitutive as well as induced total phenols and total sugars as compare with cultivated sunflower and susceptible wild sunflowers. Polyacrylamide gel electrophoretic (PAGE) isozyme analysis of defence-related enzymes showed a positive correlation of resistance with chitinase and polyphenol oxidase and a negative correlation with peroxidase.

Interspecific hybridisation and cytogenetic studies in ornamental sunflower breeding

This study examined the possibility of using wild sunflower species as a source of desirable genes in breeding the common ornamental sunflower. Crossing 7 wild species with 6 inbred lines of common ornamental sunflower produced F1 hybrid plants only with Helianthus argophyllus and H. petiolaris. The F1’s exhibited the dominant phenotype of the wild species. Cytological analysis showed irregularities in meiosis and low pollen fertility in F1 hybrids. The most frequent configuration was 15 bivalents and 1 quadrivalent and 13 bivalents and 2 quadrivalents. The presence of quadrivalents at diakinesis indicated the occurrence of translocations. In a small percentage of anaphase I meiocytes, chromosome bridges were detected resulting from inversions. The occurrence of translocations and inversions showed the differences in chromosome structure among the crossed species. Helianthus argophyllus and H. petiolaris may be useful in ornamental sunflower breeding as valuable sources of desirable genes.

Phenotype variability and inheritance of leaf shape in F1 generation of sunflower

Populations of wild sunflower species were crossed with cms cultivated lines because of their high variability. Variability was determined by measuring inflorescence diameter, ray flower number and the leaf length and width. The data was used for hierarchical cluster analysis in the SYSTAT 10 program and the obtained dendrogram was used to interpret divergence of used populations. Comparing 25 hybrid populations with parents tested the modes of inheritance. Cluster analysis divided plants in to three groups. The first ones were inbred lines of cultivated sunflower. In the middle of the cluster tree were annual wild species and the third group were perennial wild species. The mean value differences in observed traits between parents were significant. All modes of inheritance were present in Fi generation. Intermediate was the most frequent followed by equal number of partially dominant and dominant ones and in two hybrid combinations, negative heterotic effect was scored.

Sources of resistance to diseases in original material of sunflower

SUMMARY This paper summarizes the results of infection level evaluation for the most harmful sunflower diseases in Central Chernozem Region of Russia. Using annual and perennial wild sunflower species from collection as sources of resistance to pathogens has shown to be important. Various forms of cultivated sunflower have been obtained during many years work. Among them, we identified male and female sunflower lines with complex resistance. These lines also possess high general combining ability and agronomically important traits. A disease causing several extremely located necrotic spots has been registered at the end of the growing season. This kind of disease development may be considered as field resistance index.

Genotyping of helianthus based on microsatellite sequences

Analysis of microsatellite sequences was used for estimation of genetic diversity of cultivated and wild sunflower and usefulness for genotype identification, genetic purity and "hybridity range" definition. In total 13 SSRs were tested. Unique alleles for some wild sunflower species were found. Eight out of 13 SSR loci were polymorphic for the investigated inbred lines. Four of the investigated microsatellites are suitable and sufficient for genome identification and determination of parentage of hybrids. A procedure is proposed for sunflower genotype registration based on DNA-typing.

Chemical characterization of oils and meals from wild sunflower (helianthus petiolaris nutt)

AbstractChemical characterizations of oils and meals from the wild sunflower species Helianthus petiolaris Nutt and their comparison with those from cultivated sunflower (H. annuus) were performed. Seeds from indigenous populations of H. petiolaris were harvested in Argentina in different years. The analytical parameters studied were as follows: (i) FA profile, PV, p‐anisidine value, oxidative stability, phosphorus and phospholipid content, tocopherols, polar compounds, and waxes in the extracted oils; and (ii) moisture, ash, crude fiber, metals, sugars, urease activity, starch, protein, available lysine, neutral detergent fiber, acid detergent fiber, lignin, gross energy, and amino acid content in the residual meals. The products from wild sunflower seed, which yielded 27–30% oil by solvent extraction, showed some characteristics similar to the commercial products. Nevertheless, the oil had lower quality and stability owing to the high unsaturation levels and lower concentrations of antioxidant components, and the meal had a lower protein content. The phospholipid content was significantly lower than in industrial crude sunflower oils. Most of the important parameters in the meal such as available lysine, gross energy, and digestibility compared favorably with those for cultivated sunflower meals. The results showed the potential for using these meals for animal feed.

Wild helianthus species and wild-sunflower hybridization in Argentina

Two wild Helianthus species native to North America have been naturalized 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.

Roles of interspecific hybridization and cytogenetic studies in sunflower breeding

The abundance and diversity of species within the genus Helianthus offer numerous and rewarding possibilities to sunflower breeders. All annual species and a large number of perennial species may be crossed to the cultivated sunflower by the conventional hybridization method. On the other side, the divergence and heterogeneity of the genus cause considerable difficulties, such as cross-incompatibility, embryo abortiveness, sterility and reduced fertility in interspecific hybrids. Because of that, methods of somatic hybridization, "in vitro" embryo culture, chromosome doubling, etc. are frequently used for interspecific crossing. Cytogenetic studies are used for determinations of chromosome number and structure and analyses of meiosis (microsporogenesis) and pollen viability, making it possible to establish phylogenetic relations between wild sunflower species and the cultivated sunflower and enabling the use of the former in sunflower breeding. Cytogenetic studies of the sunflower have evolved from cytology through cytotaxonomy and classic Cytogenetic to cytogenetic-molecular studies. Most intensive progress of Cytogenetic studies has been associated with the use of interspecific hybridization in sunflower breeding.

Evaluation of wild sunflower species for tocopherol content and composition

SUMMARY 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% gammatocopherol. 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% betatocopherol, and 2.0% gamma-tocopherol. The maximum total tocopherol content 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 accession of H. debilis (11.8%). All other accessions contained less than 6.5% betatocopherol. 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.

Interspecific hybridization in sunflower breeding for economically valuable characteristics

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