MoRho3 Mediated Gene Expression Network In Magnaporthe Oryzae

Rice blast is one of the most severe disease in rice-growing regions of the world and become a ongoing threat to ensuring global food security.The causal fungus Magnaporthe oryzae produces appressoria which have a high internal turgor pressure and develop penetration peg in order to pierce the host surface during infection process,To understand morphogenesis and polarity differentiation of appressorium is significant for revealing the process of pathogenicity and controlling rice blast.MoRho3,a Rho GTPase,acts as molecular switches in eukaryotic signal transduction,and plays an important role in the growth of cell polarity,vesicle trafficking and infection process.Previous studies have showed that Δ MoRho3 deletion mutants affect polar growth of conidia,delay conidium germination and reduce turgor pressure in appressorium penetration and pathogenicity.Meanwhile,constitutively active mutant MoRho3-CA was defective in appressorium formation and polar growth was influenced in dominant negative mutant MoRho3-DN.Furthermore,both of them were defective in pathogenicity.However,MoRho3 regulatory networks involved in pathogenesis as well as its relative molecular mechanisms still needs to be uncovered.In order to further analyze the expression network mediated by MoRho3,transcriptome sequencing and comparison analysis were conducted for two mutants MoRho3-CA,MoRho3-DN and wild type isolate 70-15.In total,63 genes were found to interact with Rho3 in Saccharomyces cerevisiae in previous study and expression analysis for their homologous genes in Magnaporthe oryzae implies 28 genes of them were influenced.We discovered 3536 differential expression genes(DEGs)in two mutants and pathway enrichment for these gene sets suggests nucleic acid metabolism and transcription-related pathway were distinctly affected.1050 intersectant DEGs were found in two mutants and nearly 70 percent of them belong to co-down-regulated genes,GO enrichment for them proves that they are related to oxidation-reduction process.31 genes which are up-regulated in CA and down-regulated in DN were discovered and among them three melanin-related genes were found which is consistent with our morphological experiment.Meanwhile,123 genes were found down-regulated in CA and up-regulated in DN and GO enrichment for them indicates their relationship with transporter activity and transmembrane transport,and this shows that MoRho3 may directly or indirectly negatively control these categories of genes.Furthermore,GO enrichment analysis for DEGs in MoRho3-CA mutant suggests that highly significant enrichment of genes set related-to structural constituent of ribosome.Our study mainly compares the transcriptome of small GTPase Rho3 in constitutively active(CA)and dominant negative(DN)and uncovers the crucial role of MoRho3 in cell polarity,material transmembrane transport and related expression regulation network and it’s very valuable for digging out useful information of downstream protein of Rho3.