CONICET | Buscador de Institutos y Recursos Humanos

The late blight pathogen Phytophthora infestans is responsible for the most significant global disease of potato. P. infestans exhibits high evolutionary potential and rapidly adapts to overcome resistant plants. Its genome sequence reveals striking potential for genetic change, showing extensive expansion of specific families of secreted disease effector proteins. Some of these effectors can be recognized by plant immunoreceptors and are targets for disease resistance breeding. In order to establish a comprehensive overview of the genetic variation of P. infestans effectors, and to further define a set of core effectors, we initiated RNAseq transcriptome sequencing of ~15 diverse isolates. The selected isolates include representatives of various genotypes from UK, Netherlands, Mexico and Colombia, selected on the basis of relevant characteristics such as virulence spectra, aggressiveness and predominance in current European populations. We will screen the core set of in planta-induced effector genes identified in this analysis with plant immunoreceptors to maximize the durability potential of the newly identified resistances. In addition, knowledge on allele diversity of essential effectors can be used to expand the effector recognition specificity of a given resistance gene to virulent alleles. We accomplished this goal using artificial evolution by random mutagenesis. By means of this approach, we successfully expanded the recognition specificity of the Solanum demissum R3a resistance gene to a virulent P. infestans Avr3a allele and Avr3a homologs from other Phytophthora species. Furthermore, the library of R3a mutant variants we generated represents a permanent resource to screen for new resistance specificities against AVR3a homologs from various pathogen species. This pipeline illustrates how knowledge on pathogen effector biology and diversity can improve the use and deployment of late blight disease resistance.