Inheritance of resistance to a highly virulent race f of orobanche cumana wallr. in a sunflower line derived from interspecific amphiploids

Abstract

F in Spain have overcome all known resistance genes, Or1to Or5, in cultivated sunflower (Helianthus annuus L.) and are spreading rapidly. Resistance to race F of this parasitic weed has been found in wild perennial species of Helianthus and has been introgressed into cultivated sunflower. The objective of this study was to characterize the inheritance of resistance genes in cultivated sunflower derived from wild perennial species H. divaricatus and H. grosseserratus, respectively. Crosses between resistant cultivated lines and the susceptible line P21 were made, and the F1's were resistant when evaluated for broomrape resistance using a highly virulent population of race F, indicating dominance of resistance genes. Comparison of resistance of the segregating populations, F2and BC1F1, to both parents confirmed the dominance observed in the F1and indicated that resistance is under the control of a single dominant gene. This dominance of resistance genes will greatly simplify the breeding for resistance. © 2002, by Walter de Gruyter Berlin/Boston. All rights reserved.