Molecular Characterization Of A Nuclear Factor Kappa B Member,Rfrelish,in The Invasive Destructive Pest,Rhynchophorus Ferrugineus Olivier(Coleoptera,Curculionidae)

Red palm weevil,Rhynchophorus ferrugineus Olivier(Coleoptera:Curculionidae),is the most destructive pest of palm plants worldwide which has been extremely expanded into many new areas containing the southern part of China.Because it often hides inside palm trunks except for mating and oviposition,it is very difficult to detect them at the early stage of infestation.The latest evidence indicated that some field populations of R.ferrugineus had shown pesticide resistance.It is always emphasized to develop integrated pest management based on biological agents,but their efficiency is not very exciting.Elucidating the mechanisms underlying the immune response of R.ferrugineus to its natural enemies will pave the way to the development of novel control strategy targeting its immunity.In the present study,molecular characterization methods were used to detect the potential roles of a nuclear factor kappa B(NF-B)member,RfRelish,in the mediation of immune defense in R.ferrugineus.The full length cDNA of RfRelish is 2707 bp with an open reading frame that encodes 714 amino acids.Similar tDrosophila Relish and the mammalian p 100,it is a compound protein including a conserved Rel homology domain an IPT(Ig-like,plexins,transcription factors)domain and an I?B-like domain(four ankyrin repeats),the nuclear localization signal KRPR is also detected at the residues 210-213,suggesting that it has homology to Relish and it is a member of the Rel family of transcription activator proteins.Reverse transcription quantitative polymerase chain reaction analysis reveals that different copies of RfRelish mRNAs is determined in various tissues containing hemolymph,midgut,crop,head,fat body and epidermis.The expression levels of RfRelish in the immune-related tissues(hemolymph,fat body,midgut and crop)were significantly higher than those in head and epidermis.The injection challenge of Escherichia coli and Staphylococcus aureas markedly induced the expression of RfRelish.Collectively,our data suggested that RfRelish is not only involved in mediating the systemic immune response but also might be vital in regulating the homeostasis of its gut microbiota.