Functional Analysis Of Proline Metabolism-related Genes In Magnaporthe Oryzae

Proline is a multifunctional amino acid with important roles in osmotic and oxidative stress protection,protein stability maintaining,cell signaling,programmed cell death,and nutrient adaptation.In Magnaporthe oryzae,appropriate ROS generation is necessary for normal hyphal tip growth,conidial germination,and appressorium development,while accumulating too much ROS would cause cytotoxicity,therefore,precise ROS homeostasis is vitally important.Since proline and its metabolism are closely involved in keeping intracellular redox balance,it is significant to study the biological functions of proline-metabolism genes in M.oryzae,which can help us to better understand the molecular mechanism related to growth,development and pathogenicity of the fungus.Four proline metabolism-related proteins were analyzed in our study,and they were y-glutamyl kinase(MoPro1),delta-1-pyrroline-5-carboxylate(P5C)reductase(MoPro3),proline dehydrogenase(MoPutl),and a transcriptional factor involved in proline catabolism(MoPut3).Our results showed that the transcription of MoPRO1 and MoPUT1 were highly upregulated under oxidative stress.Compared with the wild type strain,△MoProl mutants exhibited obvious defect in vegetative growth,and the sensibility to oxidative stress of both △Mopro1 and △Moput1 mutants were dramatically reduced.All the deletion mutants of the four genes exhibited reduced conidiation,especially △Mopro1 mutants which showed significant reduction of conidiophore formation,and plenty of conidia produced by △Moput1 mutants showed abnormal morphologies.However,all the mutants exhibited normal pathogenicity on susceptible rice cultivar CO39.Taken together,our results suggested that MoProl and MoPutl play important roles in response to oxidative stress and conidiation process in M.oryzae.