Identification Of Psa Ⅲ Type Effector Proteins Regulating Plant Defense Response And Investigation On The Resistance Mechanism Mediated By The Effector Protein AvrRpm2

Bacterial canker disease caused by Pseudomonas syringae pv.actinidiae(Psa)is a devastating disease of kiwifruit,which is severely limiting the development of the kiwifruit industry.The type Ⅲ effector is a key pathogenic factor of Psa.Therefore,the identification of plant disease resistance regulated by effector protein is of great significance for improving the pathogenesis of Psa and developing control technologies.We cloned 21 type Ⅲ effector genes of Psa in this study.Injected into Nicotiana benthamiana,subcellular localization showed that AvrRpm2,HopAO2,HopZ3,HopAW1,HopF4 b,HopBB1-2,HopN1,AvrB4,HopAF1,HopY1 and HopAG1 were located in both the nucleus and the cytoplasm of the N.benthamiana leaf flesh cells,while HopAE1,HopD1,HopAH1,HopAA1,HopA1,AvrPto5 and HopAU1 were located in the cytoplasm.However,we could not determine the subcellular localization of HopZ5,HopAM1-1 and HopQ1 in our experimental conditions.HopZ5,HopAM1-1 and HopQ1 induced hypersensitivity(HR)in tobacco phenotypes.In order to detect the impact of Psa type Ⅲ effectors on plant disease resistance,we created 13 transgenic strains in Arabidopsis with effector proteins.For bacterial growth counts and phenotypes observed after inoculation with Pst DC3000,the showed that the HopF family of AvrRpm2 can enhance the resistance of Arabidopsis to Pseudomonas syringae Pst DC3000.In the present study,we further explored the potential mechanism of AvrRpm2 regulating Arabidopsis disease resistance.The results of PTI and ETI suggested that AvrRpm2 can enhance flg22 induced hydrogen peroxide production,callose deposition,promote AvrB and AvrPphB induced cell death.In addition,transgenic plants of Arabidopsis in disease resistance was inoculated with PstDC3000,the result showed that AvrRpm2 could not induced resistance of Arabidopsis thaliana to Pst DC3000 in mutant pmr4,mpk3 and pad4.In the mutant eds1,AvrRpm2 promoted the susceptibility of Arabidopsis to Pst DC3000.In mutant sid2 and NahG transgenic lines,AvrRpm2 still enhanced the disease resistance of Arabidopsis.In conclusion,we completed 21 subcellular localization of Psa effector proteins and response on non-host Nicotiana benthamiana,and identified 3 effector proteins inducing tobacco HR.Here,we created transgenic Arabidopsis and identified one effector protein for disease resistance in Arabidopsis.Importantly,In this study,we elucidated the mechanism of AvrRpm2 positively regulating disease resistance in Arabidopsis Thaliana at the genetic level,meaning that AvrRpm2 regulated plant disease resistance by relying on innate immune responses rather than SA mediated plant hormone resistance.