Functional Analysis Of Phytophthora Infestans Effectors PITG₁5556.2 And PITG₂1190.2

As the fourth major staple,potatoes are playing an increasingly important role in people's lives.However,diseases on potatoes pose a huge threat to the potato industry.Among them,the late blight caused by P.infestans is a serious harm.P.infestans secretes a variety of effectors to interfere with the plant's immune response to achieve the purpose of successful infection.RXLR effectors are one of the important types of effectors.The previous research found that the RXLR effectors PITG₁5556.2HLJ and PITG₂1190.2HLJ can up-regulate the expression of P.infestans on potato in the infection process.It is speculated that these two effectors play a certain role in the infection process of P.infestans.On this basis,we studied the role of these two effectors in the infection process of P.infestans and its molecular mechanism,and obtained the following results:1.Transient expression method was used to express PITG₁5556.2HLJ on Nicotiana benthamiana and potato leaves and inoculate the spore suspension of P.infestans.It was found that PITG₁5556.2HLJ can promote the colonization of P.infestans on Nicotiana benthamiana and potato.2.Transient expression method was used to co-express PITG₁5556.2HLJ with INF1,BAX,NIP,Avh238,and Avh241 on Nicotiana benthamiana leaves,PITG₁5556.2HLJ inhibited HR on Nicotiana benthamiana,indicating that PITG₁5556.2HLJ can inhibit PTI and ETI.DAB was performed on the leaves of Nicotiana benthamiana that transiently expressed PITG₁5556.2HLJ and inoculated with P.infestans.It was found that PITG₁5556.2HLJ inhibited the accumulation of hydrogen peroxide in plants.It shows that PITG₁5556.2HLJ can participate in various immune responses in plants to promote plant susceptibility.3.PITG₁5556.2HLJ transgenic potato plants were obtained through potato genetic transformation.The plant height was measured.The plant height of transgenic potatoes was significantly lower than the Desiree,indicating that PITG₁5556.2HLJ has an inhibitory effect on the normal growth of potatoes.4.A bait vector of PITG₁5556.2HLJ was constructed,and a candidate interaction protein StSMU2 was screened by the method of yeast two-hybrid sieve library.Yeast two-hybrid and BiFC were verified for the authenticity of the interaction between the PITG₁5556.2HLJ and StSMU2,and the results idicated that PITG₁5556.2HLJ and StSMU2 interact.5.Transient expression of PITG₂1190.2HLJ on Nicotiana benthamiana and potato leaves inoculated with P.infestans.The results showed that PITG₂1190.2HLJ promoted colonization of P.infestans on Nicotiana benthamiana and potato,indicating it plays an important role in the disease process.6.Using transient expression,co-express PITG₂1190.2HLJ with INF1,BAX,NIP,Avh238,and Avh241 on Nicotiana benthamiana leaves,and PITG₂1190.2HLJ inhibited the HR on Nicotiana benthamiana.The same method was used to detect the three alleles of PITG 21190.2HLJ,and all of them could inhibit the HR induced by INF1,BAX,NIP,Avh238,and Avh241 on Nicotiana benthamiana.The alleles of PITG 21190.2 in different strains are conserved for inhibiting the functions of PTI and ETI in plants,indicating that PITG₂1190.2 has an important role in the pathogenicity of P.infestans.7.PITG₂1190.2HLJ was transiently expressed on the leaves of Nicotiana benthamiana and inoculated with P.infestans.After staining the leaves with DAB,it was found that PITG₂1190.2HLJ inhibited the accumulation of hydrogen peroxide in plants.After transiently expressing PITG₂1190.2HLJ on Nicotiana benthaMiana leaves and inoculating P.infestans,the expression of genes related to the salicylic acid and ethylene signal pathways was detected.The results showed that the expression of the PR1b gene of the salicylic acid signal pathway and the ERF3 gene of the ethylene signal pathway are down-regulated.It is speculated that PITG₂1190.2HLJ inhibits the salicylic acid signal pathway and the ethylene signal pathway.PITG₂1190.2HLJ participates in multiple immune response pathways in plants and increases plant susceptibility.In summary,through the study of the effectors PITG₁5556.2HLJ and PITG₂1190.2HLJ,the functions of the two effectors were analyzed,and the functions of these two effectors in the interaction between P.infestans and the host were initially explored.Help to further analyze the mechanism of PITG₁5556.2HLJ and PITG₂1190.2HLJ,and the mechanism of host infestation by P.infestans.