Defining membrane-bound transcription factors in plant stress responses

Biotic and abiotic stresses rapidly alter water and H₂O₂ fluxes, membrane fluidity, organelle redox state, and endoplasmic reticulum (ER) proteostasis, affecting nuclear gene expression. Membrane-bound transcription factors (MTFs) and related membrane-associated pathways regulate the generation, localization, and activity of nuclear-competent forms of transcription factors through proteolysis, unconventional mRNA splicing, and post-translational regulation. This mini review examines ER-to-Golgi trafficking and proteolytic activation of bZIP17/28, IRE1-dependent splicing of bZIP60/OsbZIP50, the varied activation mechanisms of NAC/NTLs, and PIP-associated MYBs. PIP-MYB studies support transporter participation in MTF activation, although the contributions of transport activity and physical interaction remain difficult to separate. Most bZIP and NAC/NTL pathways respond to changes in ER, membrane, or organelle status. We discuss their roles in proteostasis, growth restraint, and immunity, and how pathogens exploit them. We also assess the evidence for direct transporter-MTF coupling and indirect regulation by membrane state. Their use in crops will depend on establishing how endogenous MTFs are activated and switched off, and whether the resulting responses improve yield across environments.