Regulation Of Transcription Factor NbbZIP60 In The Infection Process Of Potato Virus Y

AtbZIP60 is a transcription factor of the unfolded protein response(UPR)mechanism in Arabidopsis thaliana,which has the function of regulating plant growth and development.Heat,salt stress and pathogen induce endoplasmic reticulum stress in plant.When inducing endoplasmic reticulum stress,plant can activate the mechanism of UPR and promote inositol requiring kinase 1(IRE1)mediated-splicing of bZIP60 mRNA,form an active and truncated protein that enter nucleus to play a role,promote the expression of UPR-related genes so that it slows down endoplasmic reticulum stress and rebuilds intracellular homeostasis.Potato virus Y is one of the common viruses in tobacco.Its infection seriously decline the yield and the quality of flue-cured tobacco.There is a lack of targeted anti potato virus Y(PVY)drugs in production.Virus-induced IRE1/bZIP60 signal has not been explained in tobacco.The purpose of this paper is to study that how Nbb ZIP60 signal coordinate the growth of N.benthamiana and to reveal the mechanism of NbbZIP60 in the process of PVY infection,in order to use NbbZIP60 to improve plant disease resistance and stress resistance,to provide theoretical basis for targeted virus resistance.The main results are as follows:(1)A total of 79 NbbZIP transcription factors are identified in the whole genomics of N.benthamiana,of which 59 are verified by EST data in NCBI.Sequence alignment showes that all NbbZIP transcription factors contain a bZIP domain,and the 24 th position in the domain is lysine,indicating that lysine is a conservative amino acid that makes up the bZIP domain of NbbZIP transcription factors.NbbZIP is mainly located in nucleus.(2)By real-time fluorescence quantitative PCR,laser confocal microscope and transmission electron microscope,it is proved that NbbZIP60 is involved in the inhibition of PVY replication.PVY infection leads to changes in the structure and morphology of endoplasmic reticulum,up-regulated expression of endoplasmic reticulum chaperone gene BLP4,UPR-related genes NbbZIP28 and NbbZIP60,indicating that PVY infection induces endoplasmic reticulum stress,and cells initiate UPR,to alleviate the load caused by PVY proliferation.PVY infection activates the base deletion of mRNA in the transmembrane domain of NbbZIP60,and then it translates to an active protein NbbZIP60 S to resist the replication of PVY.(3)By virus-induced gene silencing(VIGS),CRISPR/Cas9 gene knockout and 35 s promoter over-expression,the regulation of transcription factor NbbZIP60 in PVY infection was studied.Silencing NbbZIP60 results in plant dwarf,delayed budding,and accelerates the process of PVY replication,which is beneficial to PVY infection.Transient over-expression of NbbZIP60,slows down the process of PVY replication,indicating that NbbZIP60 plays a negative role in the regulation of PVY replication and plays a promoting role in the process of plant growth and development.From the above results,it is concluded that NbbZIP60 is the UPR regulatory factor in the stress of PVY infection.In the early stage of PVY infection,UPR-related genes Nbb ZIP60 and Nbb ZIP28 are up-regulated to improve the basic defense response of the host and delay the replication process of the virus.PVY infection promotes the splicing activation of NbbZIP60 mRNA,producing the active protein NbbZIP60 S and entering nucleus to participate in plant disease resistance.NbbZIP60 can slow down the replication process of the virus,but it can not inhibit the systematic infection of the virus.