Genome-wide Analysis Of Highly Expressed TFs During Early Infection Stage By Magnaporthe Oryzae

Rice blast disease,caused by Magnaporthe oryzae is a major disease of rice,it can cause serious impact on the security and stability of world food production.The interaction of Rice with M oryzae have become the model system to study plant and pathogen interaction mechanism which contribute to in depth understand the rules of rice blast occurrence and development,thus providing the basis to control this disease.Transcription factors are important in regulation of gene expression and critical for the individual growth and development.However,whether transcription factors involved in regulation of interaction between rice blast fungus and host during the early infection stage remains unclear.There are 486 M.oryzae TFs in Fungal Transcription Factor Database,our previous study identified 96 TFs which highly expressed during the early stage of the infection by qRT-PCR.In this study,24 TF genes were knocked out to analyses their roles in fungal development and in regulation of effectors expression and their effect on pathogenicity.Our results showed that compared with the wild type 98-06 strain,the mutants ofΔMGG₀4571,ΔMGG₀4865,ΔMGG₀5518,ΔMGG₁3894,ΔMGG₁5085,ΔMGG₁4558,ΔMGG₁5021,ΔMGG₁0276,ΔMGG₁0280,ΔMGG₀9739 和ΔMGG₀8753 were defective on vegetative growth,the mutants of ΔMGG₁4558 and ΔMGG₁5021 were defective on conidiation.Rice sheath injection and rice spraying assay showed that the lesion number and infection hyphal expansion capacity significantly decreased in ΔMGG₀1853 and ΔMGG₀8753 mutants.Therefore,the transcription factors which highly expressed in the early infection stage play a very important role in vegetative growth,sporulation,appressorium formation and pathogenicity of rice blast fungus.To understand the relationship between transcription factors and expression of effector proteins,30 effector proteins were selected from 98-06 to compare their expression between 98-06 and ΔMGG₀8753.The results showed that MGG₀8753 transcription factor can regulate the expression of some effectors.For further analysis of regulatory mechanism of transcription factors on effector proteins,24 TF knockout mutants were used to infect 18 rice blast resistance genes monogenic-lines and found that ΔMGG₁3894 mutant restored fungal virulence on two monogenic genes rice lines,indicating that MGG₁3 894 may be involved in the regulation of the corresponding avirulence effector proteins expression in M.oryzae.