Monitoring Three Plasmopara halstedii Resistance Genes in Iranian Sunflower Inbred Lines

Downy mildew caused by Plasmopara halstedii is a devastating disease in sunflower worldwide. Several dominant resistance genes designated as Pl have been identified and linked molecular markers have been demonstrated. However, no information on theresistance genes is available forIranian lines. The presence of three map-based molecular markers previously proved to be linked to different resistance genes were evaluated in sunflower inbred lines. Using PCR-based and CAPS molecular markers, 26 sunflower inbred lines with different responses to P. halstedii race 100 were used to detect the presence of three resistance loci including Pl1, Pl6 and Pl13 within the lines. Molecular marker linked to Pl13 was present in some of the sunflower lines but was not correlated with the phenotypic reaction of the lines to race 100. Despite the use of three markers linked to Pl6, PCR failed to amplify any corresponding product. This data may suggest that none of the genotypes possessed Pl6 locus. Pl1-linked cleaved amplified polymorphic sequences (CAPS) were present in several resistance lines and effectively differentiated susceptible and resistant sunflower lines. Applicability of molecular markers in breeding programs revisited in disease management.