Novel Hormonal Cross - Talks in Potato Discovered By Network Analysis

Worldwide, potato is the most widely grown tuber crop and the most important non-grain food crop. Interaction between the plant and its most important pathogen, Potato virus Y (PVY), results in extensive reprogramming of the complex underlying signalling network. To comprehend the complex biological processes following PVY infection we have implemented a systems biology approach was implemented.

The knowledge from a previously manually built plant defence signalling model was complemented with dispersed information present in various databases and publications. This was combined into a large knowledge network, covering protein-protein interactions, regulation via transcription factors and non-coding RNAs; and interactions between viral and plant components.

Subsequently, the generated large knowledge network was transferred from model plant Arabidopsis to potato using orthologue information to be able to integrate it with our experimental data on potato-PVY interaction. For this, two time-series microarray datasets were used for the creation of both gene regulatory and co-expression networks.

Analyses and queries of the resulting networks allowed us to find and characterise novel nodes, novel connections and novel cross-talks between hormonal signalling pathways crucial for plant defence. The most interesting finding was previously unknown cross-talk between the salicylic and ethylene signalling pathways, indicating that the NPR1 gene expression is modulated by ethylene; which was experimentally validated in potato.

This shows that integrating the plant defence signalling model with our own experimental data offers new insights into the plant-virus interaction by expanding the knowledge on critical components of plant defence signalling.