Castanea crenata Ginkbilobin2-like as a resistance gene to Phytophthora cinnamomi infection

Many species of the Fagaceae family are susceptible to diseases caused by the oomycete Phytophthora cinnamomi. Comparative transcriptomics with resistant (Japanese) and susceptible (European) chestnut species, identified several candidate resistance genes to this pathogen. Among these genes is a Ginkbilobin2-like, which encodes for an anti-fungal protein and is putatively related to constitutive and induced defenses due to its high expression levels in Japanese chestnuts before and after P. cinnamomi inoculation. Genetic transformation and protein analysis approaches are ongoing to validate Cast_Gnk2-like as a resistance gene to P. cinnamomi. Susceptible European and American chestnuts, holm and cork oaks have been genetically transformed to overexpress Cast_Gnk2-like. Transformants were successfully obtained for all species. Characterization of the lines (copy number, gene expression) and inoculation assays are ongoing. Holm oak plants overexpressing Cast_Gnk2-like demonstrated a delay in pathogen progression after in vitro inoculation assays. The encoded protein has been expressed in heterologous systems to be isolated and used in confrontation assays with P. cinnamomi. Preliminary results point to a pathogen lag in the presence of the protein. The multidisciplinary approach in progress to functionally characterize Cast_Gnk2-like is revealing the strong potential of the gene to be used as a molecular marker to select genotypes in breeding programs and the potential of the protein as an anti-oomycete compound. The outcomes of this work will further our knowledge of the mechanisms underlying the response to P. cinnamomi and contribute to developing pathogen control strategies.