The potato–Phytophthora infestans interaction transcriptome

Late blight, caused by the oomycete Phytophthora infestans, is one of the most serious constraints to potato production worldwide. An understanding of the basic mechanisms of infection by the pathogen and of effective defence by the host, are required for informed strategies seeking either targeted chemical control of the pathogen or the development of durable resistance in the plant. An initial insight into the molecular events underpinning P. infestans–potato interactions can be gained by determining the interaction transcriptome, the sum of the transcripts from both host and pathogen that are produced during their association. To this end, projects with expressed sequence tags are ongoing and provide an overview of the genes expressed in particular growth conditions, cell types, and developmental stages, in both potato and P. infestans, and allow significant sampling of genes expressed as part of the interaction transcriptome. As many genes required for pathogenicity or resistance are transcriptionally induced, methods to enrich for up-regulated genes, such as the powerful technique of suppression subtractive hybridization based on polymerase chain reaction, are also being used to identify candidate genes required in P. infestans for infection of the host or in potato for defence against the pathogen.