Submitted to: Helia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2002
Publication Date: 7/1/2002
Citation: JAN, C.C., FERNANDEZ-MARTINE, J.M. INTERSPECIFIC HYBRIDIZATION, GENE TRANSFER, AND THE DEVELOPMENT OF RESISTANCE TO THE BROOMRAPE RACE F IN SPAIN. HELIA. JULY 2002. V. 25 (36). P. 123-136. Interpretive Summary: Sunflower broomrape is a parasitic angiosperm, totally devoid of chlorophyll, that infects the roots of sunflower plants drawing water and nutrients from them. This parasitic plant is one of the most important constraints on sunflower production in areas of eastern and southern Europe, the Middle East, Russia, Ukraine and China. The most economical and effective means of controlling sunflower broomrape is the use of resistant cultivars. However, recent studies have shown appearance of a new sunflower broomrape race in Spain, designated as F, overcoming all the resistance genes identified so far. New resistance source has been introduced into cultivated sunflower from wild perennial Helianthus species and released as four germplasm populations, BR1 to BR4, in 2001. The objective of this study was to determine the inheritance of resistance to broomrape race F in material derived from BR4. A simple on-gene control of the resistance was observed, which will graetly simplify the sunflower breeding for resistance to this new race of broomrape.
Technical Abstract: 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 valuable genetic resources for sunflower improvement. Gene transfer from wild species into cultivated background depends on the success of interspecific hybridization, F1 fertility, chromosome pairing for genetic recombination, efficient screening methods, and sufficient progenies for selection. Most wild annual species x sunflower crosses 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 prior to abortion. The chromosome homology between genomes of wild species and cultivated sunflower is high, and the meiotic chromosome pairing of wild diploid x cultivated F1 is reasonably good, except for the multivalent formation, bridges, and fragments due to translocation and inversion differences. Chromosomal doubling by colchicine treatment substantially increases the F1 fertility, improves backcrossing success, and leads to the production of amphiploids. The amphiploids have restored fertility and can be maintained by sib- pollination, and will serve as a bridge for gene transfer. Using this approach, we successfully transferred genes resistant to the new broomrape race F, which attacks all the cultivated sunflower in Spain. Inheritance studies suggest a single dominant gene provides resistance.