Function Analysis Of SABP3 And Its Interacting Protein In Plant Resistance Signal Transduction In Arabidopsis

The infection of pathogenic microorganisms causes huge losses of crop yield and quality promoting people to continuously explore plant resistance signaling pathways.,When disease-resistance plants are infected by pathogenic microorganisms,plant identification of microbial pathogens can trigger local and systemic defense responses.In order to curb pathogen invasion,some local reactions,such as rapid release of ethylene,activation of various defense genes and hypersensitive responses(HR),play direct or indirect roles.After these reactions happened,uninoculated sites will be affected and express persistent resistance of multiple pathogens which call Systemic Acquired Resistance(SAR).And(Salicylic acid(SA)is an important signal for activating SAR.Salicylic Acid Binding Protein 3(SABP3),an SA-binding protein,belongs to chloroplast carbonic anhydrase(CA)which has both CA enzyme activity and SA-binding activities can induce host resistance during pathogen infection.In this experiment,by using yeast two-hybrid technology,we have screened a protein that interacts with SABP3,which is named the Sadenosylmethionine synthases 2(SAM2 / MAT2).MAT2 is a methionine adenosine transferase,which catalyzes the production of S-adenosylmethionine(SAM)by methionine as a substrate.SAM is not only a synthesis precursor of ethylene(ET),but also a widely used methyl donor in plants for methylation reactions.We have used BiFC experiments and Pull-down experiments to verify the authenticity of the interaction between SABP3 and MAT2.The study found that the SAM content in the sabp3 mutant and the mat2 mutant was reduced,indicating that both SABP3 and MAT2 can participate in the synthesis of SAM.Meanwhile,the production rate of ethylene in sabp3 mutant was reduced and the gene expression of ethylene downstream signal pathway was significantly lower than that of the wild-type control,indicating that ethylene synthesis and downstream signaling were both affected.The inoculation experiments showed that both the sabp3 mutant and the mat2 mutant showed increased susceptibility to B.cinerea and Pst DC3000.This phenomenon implies that both SABP3 and MAT2 can involve the regulation of Arabidopsis resistance to B.cinerea and Pst DC3000.Besides,we have found that the sabp3 mutant and the mat2 mutant showed the different degree of SAR impaired phenotype.Therefore,we speculated that when plants are infected by pathogenic bacteria,SABP3 and MAT2 synergistically regulate plant resistance to B.cinerea and Pst DC3000 through protein interaction.In summary,this study studied the SA-binding protein SABP3 and its interaction protein MAT2?Through Exploring the role of SABP3 and MAT2 in the disease resistance pathway,it can provide a new theoretical basis for the study of plant disease resistance signaling pathways by using plant hormone-related proteins,which is of great significance for the further research of plant disease resistance mechanisms and cultivation of disease-resistant varieties.