Functional Analysis Of Serine/Threonine Kinase MoSch9 In Magnaporthe Oryzae

Rice is native to China and is widely grown as an important food crop around the world.Rice blast caused by Magnaporthe oryzae is a serious disease that endangers rice production and occurs in the main rice producing areas of the world.Serious it may result in have no harvest.As the rice blast fungus physiological race prone to mutation,high resistance rice varieties after a period of cultivation will mutate into susceptible varieties.A long time single chemical control is also causing fungi to produce fungicide resistance.The prevention and control of rice blast is a difficult task,so it is very important to understand the molecular mechanism of the growth and pathogenesis of M.oryzae.Target of rapamycin pathway is a highly conserved biological pathway in eukaryotic cells.Its core protein,TOR,is a Ser/Thr protein kinase.It was first discovered as a target of an immunosuppressive agent,rapamycin.The function of TOR pathway in yeast cells is achieved by TORC1 and TORC2 two protein complexes.As a major downstream effector of TORC1,the protein Ser/Thr kinase Sch9 plays multiple roles in stress resistance,longevity and nutrient sensing in Saccharomyces.cerevisiae.Sch9 can be used as a transcriptional activator of osmotic stress to participate in the regulation of osmotic stress response genes,and its activity is important for yeast cell tolerance to osmotic stress.In filamentous fungi F.graminearum Sch9 deficient mutants showed slow growth and decreased virulence.In this study,the MoSCH9 gene encoding Ser/Thr protein kinase from wild-type strain Guy11 of M.oryzae was knocked out and its biological function was analyzed.The results showed that the growth rate and sporulation rate of the knockout mutant ?Mosch9 were significantly decreased,sexual reproduction were disappeared.The ability of ?Mosch9 mycelium to infect in the host was limited and the pathogenicity was reduced.MoSch9 contribute to the resistance to cell wall stress,oxidative stress,and osmotic stress.The results of the subsequent yeast two-hybrid experiment showed that MoSch9 interacts with MoOsm1,a key element of HOG pathway in M.oryzae.We further examined the phosphorylation of protein MoMps1 in the cell wall integrity pathway of the mutant cell.And the expression levels of MoMpsl downstream transcription factors MoMigl and MoSwi6 were examined.The results showed that the phosphorylation level of MoMpsl increased and the expression of MoMigl and MoSwi6 decreased.The results of the expression of MoAtg8 in the mutant under the condition of nitrogen deficiency showed that the mutant autophagy decreased significantly.This suggests that the MoSCH9 gene may be associated with response to the stress of M.oryzae.MoSch9 plays an important role in the growth,pathogenesis,asexual reproduction,sexual reproduction of M.oryzae.And it also affects the cell autophagy of M.oryzae.At the same time MoSCH9 gene also regulates the expression of the cell wall integrity pathway related genes,resulting in the response of rice blast fungus to stress.