Tesis doctoral de Miguel ángel Cantamutto
The genus helianthus (asteraceae), native from north america comprises not only the cultivated sunflower h. Annuus var. Macrocarpus l., But also some invasive species. The wild h. Annuus ssp. Annuus (common sunflower) and h. Petiolaris nutt. (Prairie sunflower) are two annual species of the genus naturalized in central argentina. Both species merit interest as genetic resources. wild h. Annuus was probably introduced for forage purposes, but h. Petiolaris seems to have entered as a seed contaminant. Using multivariate tools, the environment and ecological conditions of the habitats were analysed. A diffusive process from each entry point is suggested, following the terrestrial infrastructure. Invasion took place in a strip of land bordering between the mollisols and entisols, the same soil orders as in the centre of origin. Within that strip, each species thrived in different microhabitats transformed by human activity such as fences, fire lines, roadsides, ditches. Helianthus annuus showed preference for microhabitats with heavy soils, while h. Petiolaris preferred sandy soils, as has been reported in north america. the hypothesis of gene flow between both wild taxa and the crop was tested by the morphological study of the progeny of off type plants and pure populations that flowered in proximity to the other taxa found under natural conditions. Between 0.5 to 18% of hybridization was found. Taking into account the dimensions of the populations found at the points of contact, these frequencies may mean thousands to millions of first generation hybrids each year. nine argentine populations of wild h. Annuus showed enough biodiversity to differentiate among them. The biodiversity contained in this new germplasm was about two thirds of that observed in a sample of wild sunflower from seventeen usa states. The accessions from argentina showed different combinations of the same traits and a longer life cycle in one accession. The oil content and fatty acid profile did not show values that could merit attention as a source of sunflower oil improvement. Other agronomic traits of interest, such as resistance to sucmov or the presence of male-sterility are currently under evaluation. seed companies probably lost interest in transgenic sunflower after research demonstrated the existence of wild populations in several regions of the world, the intense gene flow between crop and wild relatives and the probable increase of reproductive capacity due to the acquisition of transgenes. The traits under experimentation in genetically modified (gm) sunflower could improve the performance of the crop but face some market restrictions. The future of gm sunflower depends on the possibility to mitigate the effect of transgenes on the wild and weedy relatives and a change in market place acceptance, which could increase if gm means better quality for the consumer.
Datos académicos de la tesis doctoral «Agronomic study of two annual helianthus naturalized in argentina as potential sunflower crop genetic resource«
- Título de la tesis: Agronomic study of two annual helianthus naturalized in argentina as potential sunflower crop genetic resource
- Autor: Miguel ángel Cantamutto
- Universidad: Lleida
- Fecha de lectura de la tesis: 17/07/2008
Dirección y tribunal
- Director de la tesis
- Juan A. Martín Sánchez
- Tribunal
- Presidente del tribunal: ignacio Romagosa clariana
- nicolas Jouve de la barreda (vocal)
- José Martínez fernández (vocal)
- José Luis Molina cano (vocal)