SGT1 and HSP90 are essential for age-related non-host resistance of Nicotiana benthamiana against the oomycete pathogen Phytophthora infestans

The oomycete pathogen, Phytophthora infestans, is the causal agent of potato late blight, which is one of the most destructive and economically important plant diseases. We investigated the interaction between P. infestans and Solanaceous model plant Nicotiana benthamiana. Mature N. benthamiana plants were resistant to 8 isolates of P. infestans, whereas relatively young plants were susceptible to all isolates. Analysis with virus-induced gene silencing (VIGS) indicated that NbSGT1 and NbHSP90, genes essential for the function of R proteins, are required for the resistance of N. benthamiana to P. infestans. NbSGT1 was also required for the production of reactive oxygen species (ROS), hypersensitive cell death and expression of NbEAS, a gene for phytoalexin biosynthesis, induced by INF1, a secretory protein derived from P. infestans. These results suggested that N. benthamiana possibly possesses a broad-spectrum R protein against P. infestans, which requires an SGT1/HSP90-dependent mechanism, for the recognition of a conserved molecular pattern of P. infestans.

Research highlights
► Mature N. benthamiana has age-related non-host resistance to P. infestans.
► SGT1 and HSP90 are required for the resistance of N. benthamiana to P. infestans.
► EDS1 and NDR1 are dispensable for N. benthamiana resistance to P. infestans.
► N. benthamiana possibly possesses a broad-spectrum R protein against P. infestans.