Nicotiana benthamiana bZIP transcription factor NbbZIP60 is involved in plant development and resistance to PVY infection

bZIP transcription factors (TFs) play an important role in plant development and stress. This study identified 79 bZIP TFs in Nicotiana benthamiana , which were divided into ten subgroups, i.e., A, B, C, D, E, F, G, H, I, and S. bZIP60, whose promoter sequence contains cis -acting elements involved in stress response and pathogen infection, belonged to group H. The IRE1/bZIP60 pathway of the unfolded protein response (UPR) signal, a cellular defense signal, plays dual roles upon viral infection. This study confirmed that potato virus Y (PVY) infection induced endoplasmic reticulum (ER) stress-related UPR by changing ER morphology and upregulating UPR genes, (such as BLP4 , bZIP60 , bZIP28 , and NAC089 , referring to Li et al . 2017). Furthermore, bZIP60 was upregulated by spraying of salicylic acid and jasmonic acid, which are essential for systemic resistance against plant viruses. bZIP60 silencing resulted in delayed growth of N. benthamiana , increased PVY accumulation, and impaired UPR gene expression upon viral infection. bZIP60 overexpression decreased PVY infection and replication. Therefore, upon PVY infection, bZIP60 is a positive regulator that promotes plant growth and induces cellular defense signals of UPR.