Identification of co-expression gene networks controlling rice blast disease during an incompatible reaction
Rice blast disease is a major threat to rice production worldwide; the causative pathogenic fungus Magnaporthe oryzae induces rice (Oryza sativa) plants to undergo molecular changes that help them to circumvent this fungal attack. Transcriptome studies have demonstrated that many genes are involved in the defense response of rice to M. oryzae, but most of these studies focused on the screening of differentially expressed genes and the studies did not investigate the interactions among genes. We examined the interaction of rice and M. oryzae in a network context. Two near-isogenic lines were profiled at different time-points. Using transcriptome data obtained from an RNA-Seq analysis, a network based on the relationships among genes was developed through weighted gene co-expression network analysis. The analysis of degree centrality identified numerous hub genes and potential key regulators that control the rice response, providing new insights into the molecular network underlying the resistance of rice to M. oryzae infection. Additionally, a protein-protein interaction network was derived to identify complexes that might physically interact. For example, complexes of OsbHLH148/OsJAZ, OsMYB4 and some components of the phenylpropanoid pathway, as well as MYB/bHLH and NB-LRR/OsWRKYs were identified, suggesting possible roles in regulating M. oryzae infection. The combination of in silico data with transcription factor binding indicates that OsbZIP45 may serve as a driver of complex gene expression changes that result in resistance to rice blast disease, and can thus act as an integrator of multiple signals and as a coordinator of diverse cellular pathways to control the defense responses.