The Prediction And Analysis Of The Protein-Protein Interactions Between Pathogenic Fungi And Turfgrass Based On Model Species

Brown spot caused by Rhizoctonia solani, rust disease by Puccinia spp. and wilt disease by Fusarium spp. were major turfgrass diseases in China, hindering the development of our turfgrass industry. Illustrating the interaction mechanism between these phytopathogenic fungi and turfgrass will promote the implementation of integrated disease management. In our study, the genome information of Brachypodium distachyon, the model species of turfgrass, was used to predict the protein-protein interactions (PPls) between phytopathogenic fungi and turfgrass by computational methods, aiming to provide useful information for further investigation on the host-pathogen interaction mechanism. The results were obtained as follow:Based on Interolog and DDI methods, the interspeices PPI interactomes of Bipolaris sorokiniana-B.distachyon (BS-BD), R.solani-B.distachyon (RS-BD), Fusarium graminearum-B.distachyon (FG-BD) and Puccinia graminis-B.distachyon (PG-BD) were predicted and 109050,29297,109315,86498 interactions were respectively invloved in four interactomes. We refined the interactomes with simple data filtering, and reduced the BS-BD, RS-BD, FG-BD and PG-BD interactomes to 10396,4435,7892 and 17934 PPIs respectively, which improving the quality of predicted interactomes. The proteins with high degree in the refined interactomes were all pathogen proteins, most of them involved in the biological process of transport and protein folding.Based on the node features of PPI network, we compared the node degree and betweenness centrality of all pathogen-targeted proteins with those of non-pathogen-targeted proteins in the intraspeices PPI network of B.distachyon, the results indicated that the pathogen-targeted proteins tend to be the hubs or bottleneck nodes of B.distachyon PPI network. Further, the GO and KEGG enrichment analysis on pathogen-targeted proteins showed that the pathogen-targeted proteins not only involved in the biological process related to plant defense response and plant-pathogen interaction, but also were molecules in the diverse pathways such as material transport, protein modification, carbohydrate metabolic process and signal transduction.Further inspection of functionally relevant subnetworks revealed novel pathogen-host interaction candidates. In the subnet of PPls between pathogen glycosyl hydrolases family and host proteins, expect for the known interactions between pathogen Endo-1,4-beta-xylanase and plant xylanase inhibitor, there were some new PPI candidates such as pathogen endoglucanase (EG) and plant Xyloglucan endotransglucosylase/hydrolase (XTH), pathogen invertase and plant ATPase, pathogen glycoside hydrolase and plant beta-galactosidase. In addition, the analysis on the the subnet of PPIs between pathogen candidate effectors and host defense response proteins indicated that protein interactions existed between pathogen SOD enzymes, peptidyl-prolyl cis-trans isomerase (PPIases) and plant protein kinases involved in defense response.