| The evolution and regulation of pathogenic microorganisms on their life activities are embodied in the attack-defense interaction with their hosts.Pseudomonas syringae pv.tomato(Pst)is a pathogen that causes bacterial spotted disease to affect tomato yield and quality.The interaction between P.syringae pv.tomato and its host plant tomato is also an important model for studying the mechanism of pathogen-plant interaction.Pto is a resistance protein for plant against P.syringae by recognition and combination the pathogen injected effector protein AvrPtoB,AvrPto,and thus triggering downstream defense response,ultimately causing tissue necrosis in the site of infection by hypersensitivity response to prevent the colonization and reproduction of pathogens.Therefore,Pto is a pivotal protein in the pathogen-plant interaction,but the framework of the Pto-mediated molecular immunity pathway remains unclear.In the current work,tomato Pti(Pto interaction protein)genes,Pti4,Pti5 and Pti6,were cloned for plant expression vectors construction,respectively.Transient expression and western blotting of the genes were performed in tobacco leaves by Agrobacterium-mediated method.The interactions between Pti proteins and resistance preteins Pto,effector protein AvrPtoB,were then detected by means of co-immunoprecipitation in plant system.Moreover,the overexpression transgenic lines were obtained by Pti4,Pti5 and Pti6 vectors construction and genetic transformation to detect their function in tomato disease defense against P.syringae pv.tomato by Pst DC3000 inoculation.The results showed that expected bands of Pti4,Pti5 and Pti6 were expressed and their interaction with Pto,and active mutant PtoY207 D were confirmed in plant system,which indicating that Pti proteins are involved in the Pto-mediated plant immune response pathway.However,the varying degrees of interaction between Pto proteins and Pti proteins suggests that Pti4,Pti5 and Pti6 might differ in their specific functions.Further immunoprecipitation analysis revealed that Pti proteins interacted with pathogenic effector protein AvrPtoB.It is also need to further explore whether the interactions make Pti proteins to be targets of AvrPtoB or promote the recognition of AvrPtoB by plants.Furthermore,the overexpression transgenic tomato plants were obtained by Agrobacterium-mediated genetic transformation.After inoculation of pathogenic bacteria Pst DC3000 by vacuum infiltration,the specks in leaf and stem and leaf colony count significantly decreased compared with wild type plants.Thisresult indicated that Pti4 and Pti5 genes can enhance the resistance of tomato against P.syringae.The present work provided a foundation for further exploring the function of these Pto-interacted Pti proteins,understanding their roles in pathogen-plant interaction,and improving plant genetic disease resistance. |
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