Submitted to: European Conference on Sunflower Biotechnology
Publication Type: Abstract Only
Publication Acceptance Date: October 22, 2001
Publication Date: October 31, 2001
Citation: Jan, C.C. 2001. Interspecific hybridization, gene transfer, and the development of resistant sunflower to the new broomrape race F in spain. European Conference on Sunflower Biotechnology, November 4-8, 2001, Pisa, Italy. p. 37. Technical Abstract: The narrow genetic background of cultivated sunflower has been a concern for its potential for improvement, and efforts to widen its genetic base are underway. The 49 North American wild Helianthus species have long survived extreme environments and possess resistance or tolerance genes to salt, drought, insects, diseases, as well as cytoplasmic male-sterility and fertility restoration, and are believed to be the best genetic resources for sunflower improvement. Gene transfer from wild species into cultivated background largely depends on the success of interspecific hybridization, F1 fertility, chromosome pairing for genetic recombination, efficient screening method, and sufficient number of progenies for selection. Most wild annual species x sunflower combination produce F1 seeds, and can be backcrossed easily. For the more difficult perennial x sunflower crosses where hybrid seed set is rare, a two-step embryo culture technique has been established for rescuing immature interspecific embryos from abortion. Chromosome homology between genomes of wild species and the cultivated sunflower is relatively high, and the meiotic chromosome pairing of wild diploid x cultivated, F1 is reasonably good, except the multivalent formation and bridges and fragments due to translocation and inversion differences. A colchicine chromosome doubling technique has been developed to drastically increase the F1 fertility to facilitate backcrossing to the cultivated sunflower, and to produce an amphiploid by sib-pollination of the chromosomally doubled heads. The amphiploids have restored fertility and can be maintained by sib-pollination, and will serve as a bridge for further backcrosses and gene transfer.