Identification And Mechanism Analysis Of Resistance Function Of StMEE32 Against Bacterial Wilt

Ralstonia solanacearum is the pathogenic bacterium responsible for causing potato bacterial wilt,which seriously threatens potato production.Due to the diversity of R.solanacearum complex,it is difficult to obtain germplasm resources with horizontal resistance for R.solanacearum resistance breeding.Therefore,it is particularly important to analyze the mechanism of plant resistance to R.solanacearum.In this study,we focused on the key enzyme 3-dehydroquinate dehydratase-shikimate dehydrogenase(MEE32)in the shikimate pathway.Previous research found that potato MEE32 may play a role in the interaction between potato and bacterial wilt.However,its specific function and interaction mechanism have not yet been clarified.This study has achieved the following results in exploring the resistance function and mechanism of MEE32 bacterial wilt:1.Nb MEE32 is involved in the leaf development of Nicotiana benthamianaExperiments were performed after the homologous gene Nb MEE32 in N.benthamiana was silenced by VIGS.It was found that the leaves of TRV:Nb MEE32 became smaller and yellowed.Leaf measurement results showed that compared with the control TRV2:00,the leaf length and width of TRV:Nb MEE32 were significantly reduced,and the leaf shape index was significantly increased.The results of chlorophyll content measurement showed that the chlorophyll a,b and total chlorophyll content of the silenced N.benthamiana were significantly reduced.It indicated that Nb MEE32 is an essential gene for the normal development of N.benthamiana leaves.2.Nb MEE32 negatively regulates bacterial wilt resistance in N.benthamianaThe bacterial wilt disease of the silenced N.benthamiana was identified.According to the survival curve,the bacterial wilt resistance of TRV:Nb MEE32 was significantly improved compared with TRV2:00,indicating that Nb MEE32 negatively regulated the bacterial wilt resistance of N.benthamiana.3.St MEE32 is involved in potato leaf developmentConstruct the interference vector to carry out the stable interference transgene in the background of potato E3,and select Ri-26 and Ri-34 with good interference effect.Ri-34 had yellow leaves.After measuring the chlorophyll content,the chlorophyll content of Ri-26 and Ri-34 was significantly lower than that of the control E3,indicating that St MEE32 is also involved in potato leaf development.4.St MEE32 negatively regulates potato resistance to bacterial wiltThe bacterial wilt resistance of Ri-26 and Ri-34 was identified.According to the survival curve,the bacterial wilt resistance of Ri-26 and Ri-34 was significantly improved compared with that of E3,indicating that St MEE32 negatively regulated the resistance of potato bacterial wilt.5.St MEE32 interacts with Rip E1The p GBKT7-St MEE32 yeast expression vector was constructed,and the interaction with the fungus effector protein library was carried out in yeast AH109,and the interaction between Rip E1 and St MEE32 yeast was screened.Bi Fc experiments further verified the interaction between Rip E1 and St MEE32 in plants.Rip E1 may be used by Rip E1 to regulate the expression level of St MEE32,thereby influencing plant immunity and thus promoting susceptibility.Similarly,the excess vector was constructed for St MEE32 excess transgene,and OE-6 and OE-16 were used for potato resistance identification.According to the survival curve,the bacterial wilt resistance of OE-6 and OE-16 was significantly lower than that of E3.We can therefore conclude that St MEE32 also negatively regulates bacterial wilt resistance in potatoes.The results of this study further reveal the molecular mechanism of bacterial wilt resistance,which is expected to provide new ideas and strategies for breeding.