Identification of molecular markers linked to Pythium ultimum resistance genes in safflower

Pythium ultimum is a fungus pathogen that attacks many crop species such as safflower and causes damping-off. The most important method for controlling and reducing disease damages is using of genotypes with resistance genes those are either local or breeding varieties. This study was conducted in Gorgan University of Agricultural Sciences and Natural Resources to identify molecular markers associated with Pythium ultimum resistance genes in safflower. To study response to the pathogen, two genotypes (a resistant cultivar and a susceptible line) and F1 and F2 generation derived of their crosses were used. First of all by using of infected environment, F2 populations were divided into two bulks of resistant and susceptible seedlings. Suspension of 105zoospore per ml was applied to inoculate the seedlings. Symptoms of the disease were observed as seedling and root rot and also seedling damping off. In infected environment, resistant cultivar was superior than susceptible line in terms of mortality rate of seedlings; this proves the potential of resistance against pathogen in the former genotype. In order to genotyping and identify polymorphisms, the populations were grouped using bulk segregation analysis and F2 population was genotyping by using of 24 ISSR primers that used on safflower before. Based on the results, three ISSR primers showed association with resistance gene and one primer had linkage to susceptibility. The bands associated with resistance genes were observed in resistant parent, F1 and F2resistance bulk but not in susceptible parent and F2susceptible bulk. These markers can be used for finding resistance genes to Pythium ultimum in safflower and other crops.