SNP Marker Assisted Selection for Identification of Fusarium Resistant Melon Plants

Melon is an important crop cultivated in moderate climate regions of the world. One of the most important diseases of this plant is vascular wilt caused by Fusarium oxysporum f.sp. melonis (Fom). Infection of farm by this pathogen can result in huge damage around the world. Development of resistant varieties is the most effective method for disease control. Four races of 0, 1, 2 and 1,2 have been reported for this pathogen and 1 is more versatile and dangerous races especially in the north half of Iran. Garmak, as an important variety in Isfahan province, is susceptible to race 1. Single dominant gene of Fom-2 induces resistance against race 0 and 1. In this research, the resistance gene was transferred from Isabelle into Garmak using SNP marker assisted back-crossing. The screening of plants in BC1, BC2, and BC3 generations was carried out using artificial inoculation. This gene was sequenced partially in parental genotypes and resistant and susceptible alleles were discriminated. In order to verify the resistant plants survived after artificial inoculation in BC3, plants were genotyped using the SNP marker and HRM method. This method distinctly separated three genotypes (RR, Rr and rr) from each other.  The resistance of most plants was verified by molecular method. However, among resistant genotypes identified by artificial inoculation method, there were some susceptible plants identified by molecular method, indicating the more confidence of molecular method in genotyping of plants. With selfing of BC3 resistant plants and selection of homozygote resistant plants, it is possible to develop resistant Garmak variety.