Sunflower Breeding

Abstract

Sunflower (Helianthus annuus L.) is one of the important oilseed crops cultivated worldwide for its oil and confectionary purposes. Among the crops where heterosis has been successfully exploited, sunflower assumes importance as that of maize. Identification of the PET-1 cytoplasm along with the complementary fertility restoration system is a landmark achievement which paved the way for transformation of an ornamental crop to a commercial oil yielding crop. Breeding objectives are directed towards development of cultivars with high seed yield, early maturity, resistance to diseases (downy mildew, powdery mildew, rust, necrosis disease, Alternariaster leaf spot), insect pests (Helicoverpa, sucking pests) and tolerance to herbicides, besides improved content and quality of seed oil and protein. Genetic enhancement for widening the trait base exploited traditional breeding methods, mutation breeding and interspecific gene transfer. Interspecific hybridization was adopted as one of the key tools by various research groups due to the existence of a rich repertoire of genes in the wild Helianthus species, and several economically important traits such as cytoplas mic male sterility, resistance to biotic and abiotic stresses, herbicide tolerance and seed quality traits were successfully introgressed. The past two decades witnessed advancements in molecular marker technology and genomics which have been successfully used in marker-assisted breeding for simple inherited traits, while traits governed by quantitative trait loci still remain a challenge for the breeders. Despite the availability of genes in wild Helianthus species, successful transfer to cultivar germplasm is hampered by crossability between cultivated sunflower (annual diploid) and Helianthus species varying in habit (diploid perennial) and ploidy (tetraploids, hexaploids) warranting the use of genetic engineering approaches. This chapter presents a comprehensive account of the history, bot any, the extent of genetic diversity in cultivated and wild Helianthus species. Strategies are adopted for development of inbreds and hybrids, seed production methodology and progress with regard to exploitation of molecular marker and genomic resources in marker-assisted breeding.