Arabidopsis late blight: infection of a nonhost plant by Albugo laibachii enables full colonization by Phytophthora infestans. (8th July 2016) - Belhaj, Khaoula
Summary: The oomycete pathogen Phytophthora infestans causes potato late blight, and as a potato and tomato specialist pathogen, is seemingly poorly adapted to infect plants outside the Solanaceae. Here, we report the unexpected finding that P . infestans can infect Arabidopsis thaliana when another oomycete pathogen, Albugo laibachii, has colonized the host plant. The behaviour and speed of P . infestans infection in Arabidopsis pre‐infected with A . laibachii resemble P . infestans infection of susceptible potato plants. Transcriptional profiling of P . infestans genes during infection revealed a significant overlap in the sets of secreted‐protein genes that are induced in P . infestans upon colonization of potato and susceptible Arabidopsis, suggesting major similarities in P . infestans gene expression dynamics on the two plant species. Furthermore, we found haustoria of A . laibachii and P . infestans within the same Arabidopsis cells. This Arabidopsis— A . laibachii—P . infestans tripartite interaction opens up various possibilities to dissect the molecular mechanisms of P . infestans infection and the processes occurring in co‐infected Arabidopsis cells.