The integration of ER-stress and osmotic-stress signals leads to full activation of GmNAC6. A. The effect of PEG, tunicamycin or AZC on the expression of GmNAC1, GmNAC5 and GmNAC6. Three-week-old plants were treated with tunicamycin TUN (10 μg/ml, 24 h), PEG (MW:8000, 10%, 16 h) or AZC (50 mM, 16 h). The relative expression of representative genes of UPR (BiPD and CNX), osmotic stress-specific response (SMP) and senescence-associated soybean GmNAC genes (NAC1, NAC5, and NAC6) was determined by quantitative RT-PCR. Values for TUN are relative to the DMSO control treatment, and for PEG and AZC the values are relative to the H2O control; values represent the mean ± SD of three replicates from three independent experiments. B. The synergistic induction of GmNAC6 transcripts by a combination of PEG and tunicamycin treatments. Plants were treated with TUN (16 h) or PEG (10 h) alone or a combination of TUN + PEG. For the combined treatments PEG + TUN, the plants were pre-treated with tunicamycin for 6 h when PEG was added for an additional 10 h. RNA was isolated after the indicated time and quantified by real time RT-PCR, targeting the UPR-specific gene, CNX, the senescence-associated soybean genes, GmNAC3 and GmNAC6, and the integrated pathway genes, NRP-A and NRP-B. Asterisks indicate the position of additive responses. H2O and DMSO are control treatments for PEG and TUN, respectively. Values represent the mean ± SD of three replicates from three independent experiments.