Searching for resistance to Fusarium root rot in safflower genotypes using pathogenicity test and AFLP molecular markers

Safflower (Carthamus tinctorius L.) is an annual oilseed crop adapted chiefly to the warm climate areas of Iran, which recently commercial production became concentrated to produce oil. Fusarium root rot is one of the important diseases of safflower in Iran. Whereas the use of resistant cultivars is one of the main strategies for reducing the loss and damage caused by pathogens in plants, this research was conducted to study the genetic diversity of safflower genotypes using AFLP markers and to compare relative resistance to Fusarium root rot. Sixty selected cultivars and lines derived from various regions were evaluated in randomized complete block design in three replications under in vitro and green house condition. Forty nine genotypes of safflower from Iran and 11 from other countries were inoculated with a selected identified pathogenic isolate of Fusarium solani derived from safflower. Genotypes were classified into five groups based upon the type of reaction to the disease; i.e. resistant, semi-resistant, tolerant, susceptible and semi-susceptible. Genetic diversity of the genotypes was assessed using AFLP markers. The results indicated differences among genotypes for resistance to Fusarium and clustering based on this trait. A bootstrap procedure was used to compare mean distances within and between genotypes and resistance to Fusarium root rot. Clustering based on AFLP markers and phenotypic resistance traits did not indicate complete concordance, but resistance and susceptible genotypes were separated from one another and have significant differences with other genotypes.