Functional Analysis And Potential Application Of Histone Methyltransferase MoKmt3 In Magnaporthe Oryzae

Rice blast,caused by the filamentous fungi Magnaporthe oryzae,is one of the main diseases that cause serious loss of rice production worldwide.At present,the main method for rice blast control is resistance breeding,supplemented by chemical and biological control.However,it is very difficult to prevent and control rice blast because of the easy mutation of disease-resistant races,perennial cultivation of highly resistant varieties and drug resistance brought by long-term use of traditional pesticides.An in-depth understanding of the pathogenic mechanism of M.oryzae is of great significance to the prevention and control of rice blast because M.oryzae is one of the important model organisms for studying fungus-host interaction.Epigenetic modification means that DNA or histones are covalently modified causing heritable changes in gene expression under the condition that the genetic material remains unchanged.KMT3 is a type of histone methyltransferase,which plays an important role in transcriptional process,but the function in M.oryzae is unknown so far.In our research,the histone methyltransferase KMT3 of M.oryzae was identified and further investigated the role of MoKmt3 in the biological processes of regulating growth and development,pathogenicity and response to external environmental stimuli.The loss-of-function mutant ΔMokmt3 was obtained by a targeted knockout with the method of homologous recombination.In the vegetative growth stage,ΔMokmt3 grows slowly accompanied with whitening of aerial hyphae and decreased accumulation of melanin;in terms of conidia and appressorium morphogenesis,there exists defects in sporulation and appressorium formation and conidia have abnormal shapes during germination;in terms of pathogenicity,pathogenicity of ΔMokmt3 is almost lost through in vitro inoculation of barley leaves and in vivo spray inoculation of rice.These results indicate that MoKmt3 affects vegetative growth,reproductive growth and pathogenicity of M.oryzae.These results indicate that MoKmt3 is involved in the vegetative growth,reproductive growth and pathogenicity of M.oryzae.It is worth noting that deletion of this gene did not cause a significant change in H3K36me3 at protein level and we speculate that Mokmt3 may be involved in the regulation of H3K36me3 at specific target gene loci.RNA-Seq analysis shows that differentially expression genes ofΔmokmt3 play an important role in transmembrane transporter activity,amino acid metabolism,glucose metabolism and other biological processes.It is also confirmed that MoKmt3 can participate in the regulation of carbohydrate metabolism pathways of M.oryzae through carbon source substitution experiment.In addition,MoKmt3 is also involved in regulating the Osm1-mediated MAPK signal pathway and cell wall integrity.These results indicate that MoKmt3 also plays an important role when responding to adversity stress.In summary,these results indicate that MoKmt3 plays an important role in regulating growth,development and pathogenicity of M.oryzae.Moreovere,it is involved in the carbohydrate metabolism process and plays a crucial role when responding to adversity.Therefore,it can be used as a potential drug target for prevention and control of rice blast.