Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: 1/29/1999
Publication Date: N/A
Citation: N/A Interpretive Summary: Genetic resistance to broomrape has been introduced from wild sunflower species into cultivars since the early work on sunflower breeding in the former USSR. The widespread use of resistant cultivars has resulted in the appearance of new races of the parasite capable of overcoming the resistance genes already in use (Or1-Or5). Recent studies have shown an evolution of sunflower broomrape races in Spain, with a new race, designated F, overcoming all the known resistance genes identified thus far. This paper reports the reaction of advanced interspecific hybrids (amphiploids and BCnF1) and their parents, previously evaluated against known races, to an O. cernua population which included the F race. Results indicated that the wild perennial Helianthus species were immune, the interspecific amphiploids retained a high level of resistance, and the more advanced progenies segregated for resistant and susceptible plants. Those resistant plants are being selected for further evaluations and the development of resistant germplasm.
Technical Abstract: Several amphiploids and their backcrossed progenies derived from the wild species, H. angustifolius, H. cusickii, H. divaricatus, H. gracilentus, H. grosseserratus, H. hirsutus, H. maximiliani, H. nuttallii and H. strumosus, were tested for broomrape resistance under greenhouse conditions. Differential line P-1380, which carries the Or5 gene, was included as a check for virulence of the new race. One highly virulent population of broomrape collected from Southern Spain (SE-296) was used. The susceptible cultivated lines showed the highest incidence of infection. The susceptibility of P-1380 indicated a high virulence of the broomrape race tested. Wild perennial species were immune to the broomrape population used, indicating the high resistance to O. cernua by perennial species. All amphiploids, except those of H. gracilentus x P21 and H. hirsutus x P21, segregated for resistance. All backcrosses tested against SE-296 segregated for resistance, with a medium-low incidence and degree of attack, except BC1F1 of H. maximiliani which had a higher incidence and a high degree of attack. Resistance observed in the amphiploids and backcrosses is useful for breeding purposes. This material will provide genetic diversity for the improvement of cultivated sunflower. Selection for resistant individuals and chromosome number (34-51) in advanced backcrosses based on H. angustifolius, H. cusickii, H. divaricatus, H. grossesserratus and h. maximiliani will permit the development of diploids with resistance to the new Orobanche race.