Functional Analysis Of The ALPHA-glucosidase Genes In Magnaporthe Oryzae

Rice blast caused by Magnaporthe oryzae is one of the most devastating diseases of rice,which is an important limiting factor for stable yield of rice.In appropriate environmental conditions the disease can spread quickly,and cause a large area disease of rice in a short time.The reduction of production rises to more than 50%,if severe.The fungal pathogen initiates infection by the attachment of conidium to the plant surface.The conidium then germinates and produces germ tube;the germ tube tip develops into appressorium,melanin in appressorium which generates huge turgor forced invasive nail through rice epidermis into the interior of plant cells,causing diseases.The method we used to prevent rice blast is breeding resistant rice varieties,suppled with chemical control.But the races of M.oryzae are volatile,so we cannot only rely on resistant varieties.The complete genome sequence of M.oryzae has been published,which provides a good resource for the pathogenic mechanism study,making M.oryzae a model for the study of interaction between pathogen and plant.The sequencing accelerates the research on virulence related genes,which provides important theoric basis for preventing rice blast.N-linked glycosylation is a kind of glycosylation modification for newly synthesis proteins.This process is carried out in the endoplasmic reticulum(ER).Protein N-glycosylation occurs by transfer of a specific oligosaccharide(Glc3Man9GlcNAc2;G3)from a dolichol donor to asparagine(Asn)residues in the sequon AsnXaa-(Ser/Thr)of nascent polypeptide chains.The transferred oligosaccharide is then processed in the ER by the sequential action of specialized trimming enzymes,removing 3 glucose and 1 mannose residues.This process is benefit for resistance for protease,signal transduction and protein fold.Glucoside hydrolase plays a key role in this process.Glycoside hydrolases are various glycoside or oligosaccharides making general glycosidic bond hydrolysis.In this study,we identified and characterized the function of MoGls1,MoGls2 and MoGtb1,those glycoside hydrolase homologies in M.oryzae.We acquired ?MoGls1,?MoGls2 and ?MoGtb1 mutant through gene knockout.Target deletion of MoGLS1 resulted in loss the ability of sexual reproduction;Deletion of MoGTB1 resulted in a reduced mycelial growth,an increased conidial production;Deletion of MoGLS2 resulted in a reduced mycelial growth,an increased conidial production,delayed appressorium formation and loss the ability of sexual reproduction.Pathogenicity assays revealed that the?Mogls2 mutant showed significantly decreased in virulence and infectious growth.Further studies showed that the mutant was less sensitive to salt and osmotic stress,and increased sensitivity to cell wall stresses.Additionally,the ?Mogls2 mutant showed defect in cell wall integrity.Our results indicate that MoGls2 is a key protein for the development and virulence of M.oryzae,involved in the regulation of asexual/sexual development,stress response,cell wall integrity and infectious growth.