Search

Bulk segregant analysis and marker-trait association reveal common AFLP markers for resistance to septoria leaf blotch in Tunisian old durum wheat. Septoria tritici blotch (STB) caused by the fungus Mycosphaerella graminicola is currently the major foliar disease of durum wheat in Tunisia. Most of the Tunisian elite cultivars show little or no resistance to this pathogen. Recently, some Tunisian landraces including 'Agili' have been identified as highly resistant to the virulent STB pathotype, 'Tun06'. In order to identify amplified fragment length polymorphism (AFLP) markers associated with resistance to STB, we used bulk segregant analysis (BSA) in two F3 biparental populations derived from crosses between the resistant durum wheat accession 'Agili' and the susceptible cultivars 'Karim' and 'Khiar' and Association Mapping (AM) in a collection of 110 old durum wheat landraces. Out of the 24 EcoRI/MseI primer combinations tested, 4 were polymorphic between resistant and susceptible DNA pools. Screened on the parents and 9 to 12 progenies from each bulk, these polymorphic AFLP primer combinations revealed EcoACT/MseCTC-241, EcoACA/MseCTT-128, and EcoAGG/MseCTC-104 as specific alleles to resistant individuals suggesting their linkage to a gene for resistance to STB. Binary logistic regression analysis on the diversity panel showed that two AFLP markers out of the three identified by BSA were significantly associated with the resistance. EcoACT/MseCTC-241 was the significantly associated allele at P < 7.10-8 and was identified at a genetic distance of 1.2 cM to the resistance gene. This result indicates the efficiency of using landrace populations to detect potential markers for qualitative resistance.