Interspecific hyberdization and its roll in sunflower

The sunflower belongs to the genus Helianthus, Asteraceae family. The genus is large and polymorphic. During 18th and 19th centuries, a number of authors had described more than 200 species from this genus. Sunflower is one of the most important oil crop of the world. Its seed oil can be used for human consumption and also as a raw material for oleochemistry.

Sunflower production continues to face challenges from both abiotic and biotic factors. The major fimiling factor for further improvements of the genetic potentials for seed yield and oil quality is the susceptibility of the sunflower to a large number of pathogens. The genetic variability of the cultivated sunflower had been drastically narrowed.

The term “Interspecific hybridization” implies the crossing between different species of the same genus. This method is frequently used in plant breeding, especially when variability of a cultivated form has been exhausted and it become necessary to search for desirable genes in its wild relatives.

Wild sunflower are a source of genes for resistance to disease and pests in cultural species, of genes for early maturation and resistance in unfavorable environmental factors and sources of cytoplasmic male serility, RF genes and other useful characters.

Interspecific Hybridization between crop species and wild relative followed by backcrossing is commonly used in introgress desirable genes into the crop. The method has been used in breeding of improved cultivars numerous species. Interspecific hybridization is typically used for transmering resistance to disease agents, soil salinity and acidity, drought as well as for finding new sources of CMS and RF genes and the development of new sunflower idiotypes. In sunflower, the interspecific hybridization has successfully been used to produce novel cultivars with useful traits of both parents and to incorporate desirable trait of one specific to another. Advance breeding techniques are used like embryo rescue, (The cross Helianthus salicifolius x Helianthus annuus L. has been obtained by embryo culture method), poly ploidization, protoplast fusion and molecular cytogenetic methods. The level of hybridization in progeny determined using Random amplification of polymorphic DNA and Ristriction fragment length polymorphism markers.

Biotech techniques can be contributed to overcome the problems of narrow genetic base , and at the same time accelerate the breeding process e.g., embryo culture, meristem culture, enther and microscopic culture, protoplast culture, cell fusion. Significant progress has been made in identifying genes in wild species and the development of germplasm with regards to resistance to new races of downy mildew, rust, broom rape and other persistent diseases such as selerotinia stalk and head rot. In addition several cytoplasmic male sterility sources, corresponding fertility: restoration genes and new genes have been identified.