Expression of PR2, PR3 and PR5 Correlates with the Resistance Level of Potato Plants to Late Blight

Late blight (LB) caused by the fungus Phytophthora infestans (Mont.) de Bary, is one of the most economically important disease of potato crop worldwide. Cultivation of potato resistant cultivars is an effective and environmentally friendly method to control LB disease. The degree of resistance is often based on LB symptoms assessment, however molecular diagnostic could provide a more effective screening technique. We assumed that the degree of potato cultivars resistance to LB disease is correlated with defense related gene expression levels. Here, two potato cultivars with a low and severe appearance of LB symptoms on leaves were selected and cultivated under controlled conditions to analyze the constitutive expression of some important PR defense-related genes. Our data demonstrated that gene responses to LB infection were regulated differently depending on the susceptibility levels of potato cultivars. The resistant cultivar showed significantly higher constitutive expression levels of PR2, PR3 and PR5 genes except PR1. Notably, PR3 expression was much higher in the resistant cultivar when comparing with the expression of the other genes. It seems that LB symptom severity is associated with the degree of gene response in defense-related genes. Therefore, the obtained results may indicate that testing a number of defense-related genes in potato plants can be used as a useful predictor of resistance levels to LB disease.