title: NtbZIP60, an endoplasmic reticulum-localized transcription factor, plays a role in the defense response against bacterial pathogens in Nicotiana tabacum.
abstract: A spermine-based signal transduction pathway plays a defensive role against incompatible pathogens. We identified a novel spermine-responsive cDNA from Nicotiana tabacum that encodes a basic region/leucine zipper protein with a putative transmembrane domain. Identity to Arabidopsis thaliana AtbZIP60 was sufficiently high to name the novel cDNA NtbZIP60. Expression analysis revealed that NtbZIP60 is a component of the spermine-signal pathway, and is also involved in the unfolded protein response (UPR), as demonstrated for AtbZIP60. The gene product, NtbZIP60, localizes to the endoplasmic reticulum (ER) in plant cells; once the putative transmembrane domain is eliminated from the intact protein, it targets the nucleus. The putative processed form of NtbZIP60 transactivates target genes through binding to plant-specific UPR cis-elements. Expression of NbbZIP60, an NtbZIP60 ortholog in Nicotiana benthamiana, was significantly up-regulated at 6 h and later time points upon infection with the non-host pathogen Pseudomonas cichorii, while it was unaffected by infection with the compatible pathogen Pseudomonas syringae pv. tabaci. Furthermore, NbbZIP60-silenced N. benthamiana plants allowed higher multiplication of P. cichorii compared to the control plants. Taken together, the results suggest that this ER-localized transcription factor is involved in the spermine-signal transduction pathway and plays an important role in plant innate immunity.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi, 980-8577, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Tateda
authors.forename: Rei
authors.initials: R
authors.lastname: Ozaki
authors.forename: Yu
authors.initials: Y
authors.lastname: Onodera
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Koji
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Thomas
authors.initials: T
authors.lastname: Berberich
authors.forename: Nozomu
authors.initials: N
authors.lastname: Koizumi
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Kusano