Sukno, S., Jan, C.C., Melero-Vara, J.M. and Fernández-Martínez, J. M. 1998. Plant Breeding 117: 279-285.
Abstract: Interspecific hybrids and backcross generations between the wild perennial species Helianthus resinosus, Helianthus pauciflorus, Helianthus laevigatus, Helianthus nuttallii ssp, nuttallii T. & G. and Helianthus giganteus, resistant to broomrape (Orobanche cernua) and susceptible inbred lines were obtained to study crossability to cultivated sunflower and the transmission and expression of resistance to this parasitic weed. Conventional crosses with all the species tested were successful except for the crosses with diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F-1 hybrids with hexaploid species and lowest for those with the diploid H. giganteus. We evaluated F-1, BC1F1, some BC2F1 plants and the wild and cultivated parents. The wild species and interspecific hybrids were resistant to broomrape infection except for H. nuttallii, which showed segregation, indicating that the resistance is dominant. The crossability and resistance of F-1 and backcross generations of species with different ploidy levels indicate that the transfer of broomrape resistance to cultivated sunflower is feasible.
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