The Function Of Arabidopsis Thaliana Nuclear Transporter AtIMPA In Plant Immunity

Diseases in agricultural production cause huge economic losses and reduced grain yields.The utilization of plant disease resistance is an effective way to control diseases and reduce economic losses.Classical nuclear transport is the process of transporting cargo proteins from the cytoplasm into the nucleoplasm.During this process,the transport proteins importin α and importin β form a heterotrimer with the cargo protein to move towards the nucleus,and importin β leads to nucleoporins.Importin α has a functional domain that recognizes nuclear localization signals,and then mediates the involvement of cargo in the nuclear transport process.The signal transmission of plants in the immune response is inseparable from the nuclear transport mechanism.This research focuses on the Arabidopsis nuclear transport protein AtIMPA to explore its effect on the disease resistance of Arabidopsis.The main findings are as follows:(1)Arabidopsis AtIMPA belongs to the importin α family of Arabidopsis nuclear transporters.Sequence alignment and phylogenetic tree analysis showed that AtIMPA has Arm repeats and IBB domains,and is a nuclear transport protein-specific conserved domain.Bioinformatics predicted that AtIMPA was expressed in Arabidopsis roots,stems,leaves,flowers,siliques and other tissues,and the highest expression was in leaves.The roots,leaves,flowers and other tissues of Arabidopsis thaliana were detected by the fluorescence signal of AtIMPA-GFP fusion protein,and it was found that there were fluorescent signals,which was consistent with the predicted analysis results.The transient expression vector was injected into tobacco leaves for subcellular localization analysis.It was found that AtIMPA was highly expressed in the nucleus,and the localization region was consistent with the nuclear transport function of AtIMPA.(2)AtIMPA mutation reduces Arabidopsis resistance to Pseudomonas syringae pv.tomato DC3000(Pst DC3000).AtIMPA was induced to express in response to Pst DC3000.After screening mutant atimpa and overexpressing plants,inoculation with Pst DC3000 showed that AtIMPA mutation reduced the resistance of Arabidopsis thaliana.ABA and Pst DC3000 treatment showed that AtIMPA was not involved in stomatal closure.The mutant was more susceptible than the wild type after inoculation with Pst DC3000.Inoculated with Pst DC3000 for callose staining,the overexpression plants accumulated more callose than the wild type,while the mutant had the least callose accumulation,indicating that AtIMPA affects the resistance of Arabidopsis to Pst DC3000 by participating in apoplast immunity.(3)AtIMPA mutation affects the expression of SA and JA related genes in Arabidopsis.The expression levels of defense genes in Arabidopsis thaliana after inoculation with Pst DC3000 were detected,and it was found that the AtIMPA mutation significantly inhibited the expression of the SA synthesis gene EDS1 and the resistance-related genes NPR1 and PR1,and the JA signaling pathway marker genes AOC1,JAZ3,and MYC2 were also inhibited or up-regulated.The root length of the mutant was more inhibited than that of the wild type when treated with exogenous Me JA.These indicated that AtIMPA was involved in the anti-disease defense response mediated by SA and JA signaling pathways.In conclusion,this study found that the Arabidopsis nuclear transport protein AtIMPA mediates the resistance of Arabidopsis to Pst DC3000 by affecting the SA and JA pathways and the accumulation of apoplast callus.To provide a theoretical basis for revealing the mechanism of nuclear transport proteins in plant immunity.