Functional Studies Of Genes Regulated By The Homeobox Transcription Factor Htf1 In The Rice Blast Fungus

Magnaporthe oryzae is the fungal pathogen causing rice blast one of the most serious rice diseases,it is also an important model organisms in studying filamentous fungus.Conidium is the key component for successful disease spread and epidemics in the infection cycle.Whether conidia are generated or not and the conidial quantity will determine whether the plant disease occurrence and its severity.Therefore blocking the conidium formation is the effective way to control the disease.However,the formation of conidium is an extremely complex biological process,to clarify molecular regulatory mechanism of spore production process is very important.The homeobox genes are transcriptional factors and play a vital role in regulating the development and cellular differentiation in eukaryotes.Current literature suggests that deletion of the transcription factors Htf1 has resulted in complete loss of spore production capacity in Magnaporthe oryzae.We therefore set up a study to identify its possible downstream target gene during the conidiophore and conidium formation.Based on the RNA-seq data,we first comfirmed some up-and down-regualted genes by using real-time fluorescent quantitative PCR,and MoSSH4?MGG₀9210?,MoNCPl?MGG₀9211?,MoNHAl?MGG₁1124?were selected to further study incuding gene deletion and functional analysis.Results showed that Mossh4 deletion resulted in conidiation decrease about three times,suggesting that MoSsh4 is related to spore production in M.oryzae,but the deletion of Moncpl or Monhal showed no obvious changes comparing with the wildtype strain.Double deletion of Mossh4/Moncpl displayed conidiation reduction about ten times,enhanced the effect of MoSSH4 mutant in spore reduction,which revealed that MoSSH4,MoNCPl may be redundant.Taking together,MoSSH4,MoNCPl might be Htf1 downstream target genes,and need to have in-depth study.These results will further reveal the regulation mechanism of Htf1 transcription factors in spore production and lay the foundation for better control of the rice blast disease.