The Roles Of Protein Phosphatase MoRts1 Regulating The Growth,Development,and Pathogenicity Of Rice Blast Fungus

Rice is one of the most important food crops in the world,and could fit the food for more than 50%of the world’s population.In terms of production,rice has been threatened by Magnaporthe oryzae for a long time,and the occurrence of rice blast has seriously affected the yield and quality of rice.Under natural conditions,great challenges occurred during the disease control due to the rapid mutation rate of M.oryzae and the frequent occurrence of drug resistance.Analyzing the pathogenic mechanism of rice blast will lay an important theoretical foundation for the formulation of new disease prevention and control strategies.Protein phosphatase 2A（PP2A）is a heterotrimeric phosphatase composed of a catalytic subunit,a regulatory subunit and a structural subunit.As a regulatory subunit of protein phosphatase 2A,Rts1 is widely involved in a series of important physiological processes such as the regulation of cell cycle,gene transcription and protein translation.However,the biological function of the Rts1 protein in M.oryzae remains unclear.To clarify the biological function of Mo Rts1,two strains of Mo Rts1（MGG＿12130）knockout mutants were obtained by homologous recombination with Ku80 as the wild-type strain.Phenotypic analysis showed that compared with Ku80 strain,Mo Rts1mutant had significantly slower vegetative growth and significantly reduced melanin;abnormal conidia morphology and reduced sporulation;Mo Rts1 mutant was more sensitive to Congo red,but less sensitive to CFW,H₂O₂and SDS.the protoplast release of the mutant was significantly slower,compared with Ku80 strain.On CM medium,the hydrophobicity of the mutants significantly decreased.Subcellular localization revealed that Mo Rts1-e GFP was localized to the cytoplasm and septum.Pathogenicity tests showed that Mo Rts1 mutants were significantly less pathogenic to barley and rice,and q RT-PCR analysis showed that the expression levels of pathogenicity-related genes,such as Mg CDC42,Mg RHO3,and Mg RAC1,were significantly decreased in Mo Rts1 mutants.Domain deletion mutation found that B56is a key sequence that determines the function of Mo Rts1,and its deletion can lead to reduced sporulation and pathogenicity of the mutants.In addition,two different variants of Mo Rts1 were also found in M.oryzae,and using the Mo Rts1^{c DNA1}and Mo Rts1^{c DNA2},respectively,to complement the Mo Rts1 mutant,the deterative strains had lower growth rate and sporulation than Ku80 strain,suggesting that transcriptsMo Rts1^{c DNA1}and Mo Rts1^{c DNA2}may have unique functions in regulating the growth and development of M.oryzae.Further,with the help of Co-IP combined with LC-MS technology,more than 300 proteins that may interact with Mo Rts1 were identified,and 10 of them were verified by Y2H and Co-IP,and the protein such as Mo PP2Aa（MGG＿05671）,Mo ACL1（MGG＿06719）,Mo TIF32（MGG＿10192）,Moppe1（MGG＿03911）,and Mo Cpa2（MGG＿04503）have physical interaction with Mo Rts1.In summary,we here found that Mo Rts1 is an important regulator involved in the fungal vegetative growth,asexual reproduction,cell wall integrity,hydrophobicity and pathogenicity of rice blast fungus by interacting with a series of pathogenic factors.Our results will provide new clues for the understanding of the molecular mechanism of the growth and pathogenicity of M.oryzae.