Figure 1.

NO inhibits the wound-induced accumulation of proteinase Inh I in tomato leaves. A, Effect of NO donors on the accumulation of Inh I. B, Concentration dependence of SNP inhibition of proteinase Inh I accumulation induced by wounding. Fourteen-day-old plants having two expanded leaves and a small apical leaf were excised at the base of the stems and supplied through the stems with a solution of phosphate buffer alone, pH 6.5, for 1 h (control) or a buffer containing 1.0 mm SNAP, 1.0 mm SNP, 1.0 mm SNAP + 1.0 mm CPTIO, or 1.0 mm SNP + 1.0 mm CPTIO for 1 h. All experiments were carried out under light (300 μEm⁻² s⁻¹). Plants, except controls, were wounded twice at the middle of each expanded leaf, perpendicular to the main petiole and were incubated in water under light as described in “Materials and Methods.” Proteinase Inh I levels in leaf extracts were assayed immunologically in leaf juice 24 h later. Data are means ± sd; n = 6.