Breeding progress in sunflowers: the contribution of genetic resources within the genus Helianthus

The sunflower varieties currently grown have an average seed yield of 153 per cent of that of the first hybrids from the 1970s; the potential yield gain of more than 1 per cent per year continues. There has also been an increase in oil content of around 1.5 percentage points compared with the previous 20 years. As the genus Helianthus comprises 50 species, including wild sunflower and other annual species that readily hybridise with cultivated genotypes, some of the cultivated genetic resources may be the result of intentional or unintentional introgression. Quantitative and polygenic yield gains are likely to have originated from cultivated sunflowers to date, whilst qualitative changes stem from wild species, the most significant of which are cytoplasmic male sterility, restoration, branching and resistance to downy mildew and broomrape. The potential future contributions of these resources to variety development are discussed.