Genome-scale Solanum spp. - Ralstonia solanacearum interactome reveals candidate determinants for host specificity and environmental adaptation

Ralstonia solanacearum species complex (RSSC) is a bacterial group of aggressive and destructive plant pathogens. RSSC strains show a broad host range and adaptation to different environments. The key machinery for RSSC virulence is the Type III secretion system, which enables the secretion and injection of specialized proteins (Type III-secreted effectors or T3Es) into plant cells. T3Es interact with host plant proteins altering the normal metabolism of plant cells and reducing the plant defences. Recognition of protein–protein interactions (PPIs) is fundamental to understanding the pathogenic process and adaptation to different hosts and environmental conditions. Here, we used an in silico approach to describe PPIs between two system models, T3Es of R. pseudosolanacearum GMI1000 and Solanum lycopersicum proteins and T3Es of R. solanacearum UY031 and Solanum tuberosum proteins. Matching results of two independent analysis methods (interolog and domain-based method) employed to detect PPIs were taken as verified interactions. Results show that 12,261 PPIs are possible involving 11 T3Es. A comparison analysis of PPIs between the two system models allowed us to find some T3Es homologs which are differentially interacting with plant proteins and may explain hosts specificity and environmental conditions of RSSC. These T3Es interact with a wide variety of plant proteins that play a central role in immune responses, intracellular signalling, and metabolic processes.