Genetic diversity of pistachio cultivars and genotypes in terms of resistance to crown and root rot (Phytophthora drechsleri) and its relationship with .SCoT molecular markers

Knowledge of genetic diversity along with the management of germplasm can be used to select genotypes in breeding programs and to protect plant genetic resources. Molecular methods, along with multivariate statistical methods, have a high potential for studying relative relationships, evolution and genetic variation of plants. In this research, 20 pistachio cultivars and genotypes were evaluated in the greenhouse for root and crown rot (gummosis). The traits; disease score, mortality and dry weight were measured. Twelve SCoT primers were used to evaluate the genetic diversity of these cultivars in response to gummosis. The results of greenhouse experiment, divided the cultivars into four groups as: resistant, moderately-resistant, moderately-sensitive and sensitive. The results showed that the SCoT primers, produced 122 loci, of which 105 loci were polymorphic. Cluster analysis of genotypes based on obtained bands did not fit well with phenotypic grouping. In order to identify the bands that have the most relationship with phenotypic attributes related to gummosis, PLS and stepwise regression methods were used. Through stepwise regression, 7 loci were entered into the model, which explained the resistance to gummosis by77 to 86 percent. By cluster analysis based on the reduced variables (7 markers), two groups were obtained that association analysis (contingency table) showed association between this grouping with the phenotypic grouping. These 7 loci greatly explained the genetic variation of pistachio genotypes in response to gummosis disease. In general, according to the results, SCOT12, SCoT16, SCoT17 and SCoT20 primers could be used to study the genetic diversity of pistachio cultivars against gummosis.