DNA polymorphism of wild sunflower accessions highly susceptible or highly tolerant to white rot on stalk

Abstract

DNA polymorphism in accessions of Helianthus mollis, Helianthus rigidus and Helianthus tuberosus differing in level of resistance to stem white rot caused by Sclerotinia was evaluated in reactions with two RAPD primers, C04 and C15, selected for their potential linkage with resistance to Sclerotinia. In total, 36 fragments using both primers were generated. All fragments generated by C04 were polymorphic, while 5 fragments out of 11 generated by C15 were monomorphic. Two major clusters were identified on the phenogram generated by UPGMA analysis, one comprising plants of H. mollis 1298, and the other where all other accessions were grouped. In order to check and statistically confirm any significant association of specific fragments either with resistance or susceptibility, contingency coefficient test was done. Out of 36 fragments generated, 26 were significantly associated with resistance/susceptibility. Fragment C04-950 bp was found to be significantly associated to susceptibility, as it was generated only in susceptible accessions, while fragment C04-1200 bp was found to be associated with the resistance, as it only occurred in H. mollis accessions. The selected markers should be checked and results verified in further studies including higher number of wild sunflower accessions differing in their reaction to stem white rot caused by Sclerotinia.