Characterization Of Moyvh1 In Development And Pathogenicity Of Rice Blast Fungus

Food securing for an ever growing word population is one of the main global challenges in our century.Generally,crop yield is not only threatened by climate change or natural catastrophes but also by plant pathogens which have the capacity to completely destroy the harvest.Treatments with chemicals to control diseases are expensive and thus not applicable throughout the world and in addition might impact the environment in an unforeseeable fashion.Therefore an ideal way to guarantee reliable harvests would be to provide plants with a genetic constitution to naturally withstand pathogen attack.To generate such smart plants an in-depth knowledge of the molecular requirements of pathogens to cause disease is essential.The fungal plant pathogen Magnaporthe oryzae is capable to destroy each year rice harvests that otherwise could have feed 60-million people and was ranked as the no.1 plant pathogen for its scientific/economic importance.The life-cycle of M.oryzae is rather complicated encompassing different stages in which the fungus initially feed from living host tissue but later-on produces toxins leading to host cell death.This infection strategy is referred to a hemi-biotrophy.Despite roughly 20 years of research,the infection process of the microbe on its host plant is not fully understood at the molecular level.Protein phosphatases are critical regulators in eukaryotic cells.For example,the budding yeast Saccharomyces cerevisiae dual specificity protein phosphatase(DSP)ScYvhl regulates growth,sporulation,and glycogen accumulation.Despite such importance,functions of Yvhl proteins in filamentous fungi are not well understood.In this study,we characterized MoYvhl,an Yvhl homolog in the rice blast fungus Magnaporthe oryzae.Deletion of the MoYVH1 gene resulted in significant reductions in vegetative growth,conidial production,and virulence.The AMoyvhl mutant also displayed defects in cell wall integrity and was hyposensitive to the exogenous osmotic stress.Further examination revealed that the ?Moyvh1 mutant had defects in appressorium function and invasive hyphae growth,resulting attenuated pathogenicity.Interestingly,we found that Mo Yvhl affects the scavenging of host-derived reactive oxygen species(ROS)that promotes M.oryzae infection.Finally,overexpression of the phosphodiesterase MoPDEH suppressed the defects in conidia formation and pathogenicity of the ?Moyvh1 mutant,suggesting MoYvhl could regulate MoPDEH for its function.The accumulation of the reactive oxygen species(ROS)in rice is important in its interaction with the rice blast fungus M.oryzae during which the pathogen scavenges ROS through the production of extracellular enzymes that promote blast.We previously characterized the MoYvhl protein phosphatase from M.oryzae that plays a role in scavenging of ROS.To understand the underlying mechanism,we found that MoYvhl is translocated into the nucleus following oxidative stress and that this translocation is dependent on MoSsbl and MoSszl that are homologous to heat-shock protein 70(Hsp70)proteins.In addition,we established a link between MoYvhl and MoMrt4,a ribosome maturation factor homolog whose function also involves shuttling between the cytoplasm and the nucleus.Moreover,we found that MoYvhl regulates the production of extracellular proteins that modulate rice-immunity.Taking together,our evidence suggests that functions of MoYvhl in regulating ROS scavenging require its nucleocytoplasmic shuttling and the partner proteins MoSsbl and MoSszl,as well as MoMrt4.The reactive oxygen species(ROS)accumulation in rice is required for the interaction between plant and the rice blast fungus Magnaporthe oryzae.We found that MoYvhl regulated the maturation of ribosome to synthesis the extracellular proteins to inhibit the host-derived defense.However the identification of these extracellular proteins remains unclear.Here,we identified a Yvhl-regulated extracellular protein,Mo Yep1 which regulated the pathogenicity of M oryzae.To further understand the mechanism by which the M oryzae response the host-derived ROS to utilize the MoYepl,we used the transcriptome of ?Moatf1 mutant and found MoAtfl bind with MoYEP1,MoPTPl and MoPTP2.MoPtpl and MoPtp2 regulated the pathogenicity of M.oryzae and dephosphorylated the MoOsm1 which Phosphorylated the MoAtfl under oxidation.And we also found that the phosphorylated MoAtfl controls the initiation of transcription of both MoPTPl and also MoPTP2 under oxidation These results can provide evidences for revealing the pathogenesis of rice blast fungus.It is also valuable finding for characterization of virulence effectors and understanding their functions against host defense response to other pathogenic fungi.