Sunflower Breeding for Resistance to Abiotic and Biotic Stresses

Due to a specific structure of its main organs (root, stem, leaves, and head), sunflower can be successfully grown on marginal soils and in semiarid conditions, and it is more resist‐ ant to abiotic stresses, than other field crops. Unfortunately, it is very sensitive to biotic stresses. In sunflower breeding for resistance to abiotic stresses, the greatest progress has been made in selection for drought resistance. Breeders use over 30 different parameters in sunflower screening for drought resistance, with physiological ones being the predomi‐ nant type. The best breeding results have been achieved using the phenomenon of staygreen, with the added bonus that this method incorporates into the cultivated sunflower not only drought resistance but resistance to Macrophomina and Phomopsis as well. The di‐ versity of the wild Helianthus species offers great possibilities for increasing the genetic resistance of the cultivated sunflower toward abiotic stresses. In using wild sunflower species in sunflower breeding for drought resistance and resistance to salinity, best re‐ sults have so far been achieved with H. argophyllus and H. paradoxus, respectively. In ad‐ dition to the use of wild Helianthus species, sunflower breeding for abiotic stress resistance should also make more use of molecular breeding techniques. More progress has been made in sunflower breeding for heat resistance than in that for cold resistance. Specific breeding programs dealing with sunflower resistance to mineral deficiency and mineral toxicity have yet to be established. Concerning biotic stresses, the main problem in sunflower cultivation is caused by fungal diseases. Genetic variability of cultivated sunflower is very low and deficient in diseaseresistance genes. Due to wild sunflower species of the Helianthus genus, genes that con‐ fer resistance to certain diseases were discovered and incorporated into the genotypes of the cultivated sunflower. Based on the wild species, genes were found that confer resist‐ ance to Plasmopara halstedii, Puccinia helianthi, Verticillium dahliae, V. albo-atrum, and Erysi‐ phe cichoracearum. Furthermore, wild sunflower species provide a high level of tolerance (field resistance) to Phomopsis/Diaporthe helianthi, Macrophomina phaseolina, Albugo erago‐ pognis, and Alternaria ssp. Sources of resistance to other harmful diseases are sought after within wild sunflower species. © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. With the use of one wild species of H. annuus from Kansas (USA.), genes conferring re‐ sistance to a group of imidazolinone (IMI) or sulfonylurea herbicides were discovered. Moreover, similar genes were found through induced mutations. These sources of resist‐ ance provide successful control over a broad spectrum of weeds, which infest sunflower crops, including broomrape. The growth of the parasitic weed sunflower broomrape (Orobanche cumana Wallr) is a ma‐ jor issue in sunflower production, especially in Central and Eastern Europe, as well as in Spain. Six races of broomrape have been detected (A, B, C, D, E, and F) and dominant resistance genes (Or1, Or2, Or3, Or4, Or4, and Or6) were found in wild sunflower species. During the last 4–10 years, new virulent races of broomrape emerged in several European countries. Geneticists and breeders work on finding the sources of resistance to the new broomrape races in wild sunflower species. Numerous insect species cause economic damages during sunflower production, espe‐ cially in North America (the homeland of sunflower). Homoeosoma species are the most widespread insects that infest sunflower. Homoeosoma nebulella infests sunflower in Eu‐ rope and Asia, while infestation with H. electellum poses a major problem in USA, Cana‐ da, and Mexico. Based on the use of wild sunflower species H. tuberosus, genes conferring resistance to Homoeosoma species were incorporated. Sunflower has an armored layer in the hull, which provides resistance to this insect. Sources of resistance to other economi‐ cally harmful insects are sought after. New methods in biotechnology, particularly marker genes, have been frequently used in breeding for abiotic and biotic stresses.