Functial Characterization Of Transcription Factor Moswi6 In Magnaporthe Oryzae

The filamentous fungus Magnaporthe oryzae causes rice blast, the most serious disease of cultivated rice. Functional genomics approaches are providing new insight into the biological characteristic and molecular pathological mechanism of the fungi and leading to the prospects for sustainable control of rice blast. Transcription factors are key proteins which regulate gene expression and are of great value for study. Studying the molecular mechanism of transcription factors underlyging growth, development, and pathogenicity of M. oryzae will help research to find novel targets of chemical control and provide new sight and good idea for designing comprehensive management of Magnaporthe oryzae.Mitogen activated protein kinase (MAPK) cascades are critical components of signal introduction pathways in eukaryotic organisms. In Saccharomyces cereviaise, the Slt2p MAPK pathway regulates cell wall integrity and the response to oxidative stresses. Because the fungal cell wall is a good target for antifungal drugs, study of this MAPK pathway, especially the down-regulated transcription factor, may yield new targets for developing disease control.In Saccharomyces cereviaise, the Slt2p MAPK pathway regulates cell wall integrity and the response to oxidative stresses. Because the fungal cell wall is a good target for antifungal drugs, study of this MAPK pathway may yield new targets for developing disease control. In M.oryzae, the Mpsl MAPK is essential for conidiation, appressorial penetration, and plant infection. A gene may downstream from Mps1 was cloned in M. oryzae disignated as Moswi6. Southern blotting revealed that there was a unique copy of gene in the genome of M. oryzae. The phylogenetic analysis revealed Moswi6 was much divergent to yeast protein Swi6 though both of them have a similar domain organization Yeast two-hybrid assays proved that Moswi6 was able to interact with Mpsl, a MAPK protein in M.oryzae, suggesting that Moswi6 was a component of singnaling mediated by Mps1. Targeted gene deletion of Moswi6 resulted in many developmental defects, including vegetative growth, conidial germination, appressorium formation, and appressorium-mediated penetration. Turgor in appressorium of the mutant was decreased and the mutant attenuated virulence on rice. In addition, the mutant displayed defects on cell wall integrity. Furthermore, theΔMoswi6 mutant was hypersensitive to exogenous oxidative stress. The activity and transcription of extracellular enzymes including peroxidases and laccases were severely decreased in the mutant. These results suggested that Moswi6 may govern growth, development, and full virulence in Magnaporthe oryzae.