Fig. 3.

Local ER stress ignites the UPR systemically, mostly in a shoot-ward direction. a Diagrams illustrating the Arabidopsis shoot–root split culture system in which the shoot and root of an intact seedling are exposed to separate growth media with different chemical conditions: mock DMSO (D) or 0.5 µM Tm (T, Tunicamycin). T/D denotes shoot on Tm-containing medium and root on DMSO-containing medium; conversely, D/T denotes shoot on DMSO-containing medium and root on Tm-containing medium. b Quantitative RT-PCR analyses of UPR markers in 14-day-old wild-type seedlings treated with DMSO or 0.5 μM Tm for 24 h as described in a. Values are presented relative to non-treated control (0 h), which was set to 1. Transcription of UBQ10 was used as internal control. Error bars represent s.e.m among three biological replicates. Data significantly different from the corresponding control are indicated by asterisks (*P < 0.05, ****P < 0.0001, NS, nonsignificant; Unpaired t-test). c Quantitative HPLC/MS analyses of Tm content in shoot and root of seedlings after treatments as described in a in a shoot–root split culture system. The numbers over the histograms express ng g⁻¹ fresh weight (F.W.). Data significantly different from the corresponding control are indicated by asterisks (**P < 0.01, NS, nonsignificant; Unpaired t-test)