Cloning And Functional Analysis Of MgATG9 In Magnaporthe Grisea

Magnaporthe grisea(Hebert)Barr,is well-known as the efficient and devastatingagent of rice blast.A deep understanding of the molecular background of this fungusis beneficial for the control of rice blast.Ever more powerful molecular geneticanalysis of the rice blast fungus brings to a comprehensive understanding of themolecular basis of host-pathogen interactions in rice blast.Blast is thus developed as amodel system for the study of interactions between an economically important cropplant and a damaging fungal pathogen.Recent research demonstrated the involvement of autophagy within the processof the cell death of the conidium during the appressorium development.Autophagy isa ubiquitous degradation process.Only under some instances,autophagy is induced.Long-lived proteins and organelles are sequestered within double-membrane vesiclesthat deliver the contents to the lysosome/vacuole for degradation and recycling of theresulting macromolecules.Autophagy is a conserved process among many species,andsome genes related to autophagy could be conserved either.Here,in this paper,weisolated and cloned MgATG9 gene,which is a homolog of ATG9 gene inSaccharomyces cerevisiae.The functional analysis of MgATG9 gene in the infectionprocess of rice blast were discussed.A sequence homologue was isolated by using the amino acid sequence ofScATG9 searching against M.grisea genome databases,assigned MgATG9.The fulllength of MgATG9 ORF and cDNA clones were obtained by PCR strategy.Nucleotidesequence analysis revealed a coding sequence of 2754 nt,putatively coding a 918amino acid peptide,containing a conserved apg9 domain.Autophagy was blocked in theâ–³mgatg9 mutant,in which MgATG9 gene wasdeleted by targeted gene replacement;the mutantâ–³mgatg9 also showed delayedgermination of conidia,lower turgor pressure of the appressorium.Theâ–³mgatg9 lostits ability to penetrate and infect the two tested host,namely rice and barley.Theseproperties were restored when re-introduced MgATG9 coding sequence into themutants.In summary,MgATG9 plays a significant role in autophagy of M.grisea,which isnecessary for normal development of conidia and appressoria and pathogenicity of M.grisea.