Allelic Variation and Selection in Effector Genes of Phytophthora infestans (Mont.) de Bary

Phytophthora infestans is a devastating plant pathogen in several crops such as potato (Solanum tuberosum), tomato (Solanum lycopersicum) and Andean fruits such as tree tomato (Solanum betaceum), lulo (Solanum quitoense), uchuva (Physalis peruviana) and wild species in the genus Solanum sp. Despite intense research performed around the world, P. infestans populations from Colombia, South America, are poorly understood. Of particular importance is knowledge about pathogen effector proteins, which are responsible for virulence. The present work was performed with the objective to analyze gene sequences coding for effector proteins of P. infestans from isolates collected from different hosts and geographical regions. Several genetic parameters, phylogenetic analyses and neutrality tests for non-synonymous and synonymous substitutions were calculated. Non-synonymous substitutions were identified for all genes that exhibited polymorphisms at the DNA level. Significant negative selection values were found for two genes (PITG_08994 and PITG_12737) suggesting active coevolution with the corresponding host resistance proteins. Implications for pathogen virulence mechanisms and disease management are discussed.