Function Analysis Of Two Laccase Genes In Magnaporthe Grisea

Laccase are blue multi copper-containing phenol oxidase widely distributed in plants and fungi.Most of laccase contain three multicopper oxidase conserve domains. In higher plants,laccase are involved in lignin degradation.It has.been reported that during the process of studying pathogenic mechanism of Cryphonectria parasitica and Cryptococcus neoformans,they consider that laccase might involve with pathogenesis.So we speculate that laccase might also play roles in regulating pathogenicity in Magnaporthe grisea.Based on this assumption,we blast the Neurospora crassa laccase conserved amino acid sequence in the M.grisea genome database,16 putative laccase-like proteins were obtained.Gene Mgg₀0551.5 is annotated as similar to laccase in the database,and gene Mgg₀2876.5 shows expression in the appresorium stage in expressed sequence tag(EST)annotation.As we speculate that laccase might relate to appresorium melanin production during M.grisea infection.So we choose these two genes to study laccase function in M.grisea.Bioinformatic analysis shows that gene Mgg₀0551.5 and Mgg₀2876.5 might encode laccase and it could be secreted.Furthermore,we use gene knock out technique to study the possible genetic function gene Mgg₀0551.5 and Mgg₀2876.5 control.We construct the Mgg₀0551.5 and Mgg₀2876.5 gene knock out vectors,and obtain knock out mutants:⊿MG0551-13 and⊿MG2876.A slight decrease of laccase activity was observed in gene knock out mutant⊿MG0551-13 and⊿MG2876,when compared to its wild-type strain,we consider that it might due to overlapping in gene function. These mutants were not affected in growth rate,conidiation and pathogenicity too, which might indicate that gene Mgg₀0551.5 and Mgg₀2876.5 are not essential for the differentiation and development in M.grisea.Double or multiple deletions and proteins expression change observation are necessary to fred out the exact function of laccase in M.grisea.