Analysis of proteins differentially accumulated during potato late blight resistance mediated by the RB resistance gene

The RB gene, cloned from the wild diploid potato species Solanum bulbocastanum, confers resistance against the late blight pathogen, Phytophthora infestans. We examined changes in the proteome of potato leaves in response to inoculation with P. infestans. A nearly isogenic system comprised of susceptible Solanum tuberosum cultivar ‘Katahdin’ and resistant transgenic potato (cv. ‘Katahdin’) carrying a single copy of RB was utilized for this study. Comparative proteomic analysis revealed the presence of only 12 protein spots with a significant difference (≥ twofold) in relative abundance in resistant and susceptible potato plants after inoculation with P. infestans. Five out of the 12 identified proteins have putative roles in photosynthesis and stress responses. Silencing of these genes in Nicotiana benthamiana had no impact on RB-mediated induction of the hypersensitive response (HR). However, we found that silencing of molecular chaperone HSP90 led to the inability of RB to induce the HR after recognition of the P. infestans effector IpiO in planta.