RAPD MARKERS FOR A SUNFLOWER RUST RESISTANCE GENE

An F-2 population of sunflower (Helianthus annuus L.) was tested for s egregation of a gene conferring resistance to sunflower rust (Puccinia helianthi) Australian Race 0 (North American Race 1). The resistant p arent, RHA279, of this cross was thought to possess a single dominant resistance gene to this race. Genetic analysis confirmed that this pop ulation was segregating for a single dominant gene, the R1 gene, for r esistance to this race of the pathogen. Using bulked segregant and RAP D analyses, two markers were identified which co-segregated with the r ust resistance gene in the F-2 population. These markers, designated O T06(950) and OM12(850), are linked to the rust resistance gene at a di stance of 4.5 cM and 26 cM, respectively, with the markers situated on e either side of the gene. The availability of markers closely linked to this gene will greatly enhance selection for the gene in future bre eding programs, and especially assist efforts to pyramid the gene with other rust resistance genes to produce sunflower varieties with more durable resistance to rust.