RAPD markers for a sunflower rust resistance gene

An F-2 population of sunflower (Helianthus annuus L.) was tested for segregation of a gene conferring resistance to sunflower rust (Puccinia helianthi) Australian Race 0 (North American Race 1). The resistant parent, RHA279, of this cross was thought to possess a single dominant resistance gene to this race. Genetic analysis confirmed that this population was segregating for a single dominant gene, the R1 gene, for resistance to this race of the pathogen. Using bulked segregant and RAPD analyses, two markers were identified which co-segregated with the rust resistance gene in the F-2 population. These markers, designated OT06(950) and OM12(850), are linked to the rust resistance gene at a distance of 4.5 cM and 26 cM, respectively, with the markers situated one either side of the gene. The availability of markers closely linked to this gene will greatly enhance selection for the gene in future breeding programs, and especially assist efforts to pyramid the gene with other rust resistance genes to produce sunflower varieties with more durable resistance to rust.