Figure 1.

Efficient induction of cell death in soybean cells requires a balance between ROI and NO production. (a) Generation of NO by SNP. (b–d) Cell death in cell suspensions in the presence of different concentrations of NO and ROI. In b and d, cells were agitated at 100 rpm; in c, cells were agitated slowly (60 rpm) and challenged with 10⁸ P. syringae pv. glycinea carrying avrA (Psg). The final concentrations of indicated reagents were: 50 μM salicylic acid (SA), 4 μM cantharidin (CA), 100 μg of yeast elicitor (YE), 500 μM glucose + 0.5 units⋅ml⁻¹ glucose oxidase (G/GO). Each datum point is the mean and standard deviation of three replicates. Experiments were repeated three times with similar results. Suppression of cell death at either supraoptimal SNP or ROI concentrations as well as its reactivation by balancing the binary signal system were all significant over appropriate controls by the Student's t test (P < 0.001).