Characterization Of BZIP Transcription Factor MoGcn4 In Magnaporthe Oryzae Andeffect Of Chemical Compound Sporothriolide On Magnaporthe Oryzae

Rice is the main food crops in the world.Rice diseases seriously affect the rice production in China.Rice blast caused by fungus(Magnaporthe oryzae)is one of the most devastating diseases of rice.The global annual losses caused by rice blast accounts for about 10%-15%of yield and the economic losses amounting to billions of dollars.At present,people control rice blast mainly by chemical pesticides or cultivation of resistant varieties.Since the diversity and variability of the rice blast fungus races,resistant variety or chemical will lose its utilization value after several years.Therefore,the prevention and control of rice blast is one of the difficult problems in rice production from beginning to end.An important prerequisite for the control of the pathogen is to understand the molecular mechanisms of development and pathogenic processes.In eukaryotic cells,most proteins involved in extracellular secretion and membrane protein will modification in the endoplasmic reticulum.When the misfolded or unfolded proteins accumulated too much in the endoplasmic reticulum(ER),ER stress response pathway will be activated.Cells will initiate the UPR(unfolded protein response)pathway to response the accumulation proteins.In this study,we focused on the function of bZIP transcription factor MoHacl(homologous to yeast Hac1)in M.oryzae.The results showed that MoHac1 was involved in UPR signaling pathway and was important for the growth,asexual development,pathogenicity and response to oxidative stresses in the rice blast fungus.In Saceharomyces cerevisiae,Gcn4 and its activator Gcn2 are required for activation of a majority of UPR targetgenes during ER stress.Both Hac1 and Gcn4 bind the promoter region of target genes and activation their transcription.In S.cerevisiae,Gcn4 plays crucial roles in amino acid biosynthesis,cell wall integrity and oxidative response.Here,we identified and characterized MoGcn4 inM.oryzae.The results showed that deletion of MoGCN4 resulted in significant decrease in conidial production and pathogenicity.In addition,the deletion mutant was sensitive to oxidative stresses but showed no difference to cell wall disturb agents and the ER stress inducer.These results indicated that MoGcn4 is a key regulator during the development and infection of M.oryzae.Sporothriolide wasasecondary metabolites of endophytic fungi Nodulisporium sp.Multiple sections of genus(Nodulisporium)fungi belong to Ascomycota(Ascomycota)sordariomycetes(Sordariomycetes)xylariales(Xylariales)xylariaceae(Xylariaceae).In this study,we test theeffectof sporothriolide on conidial germination and pathogenicity ofM.oryzae.The results showed that 0.25ppmsporothriolide have no effect on the germination of conidia,while 2.5ppm 25ppm sporothriolide could inhibit conidial germination completely.For virulence test,lOppm and 20ppm sporothriolide showed no effect on the pathogenicity of M.orzyae.When the concentration of sporothriolide was 50ppm,the infection ability of the pathogen was significantly decreased in comparison to the untreated control.These results indicated that sporothriolide could as a potential fungicide to control the rice blast disease.