Figure 2.

Alkaline hydrolysates of cutin from various plants elicit H₂O₂ production and also enhance the H₂O₂ activity of a fungal H₂O₂ elicitor, similar to cucumber surface wax. All activities were calculated relative to the activity of fungal elicitor (10 μg mL⁻¹) determined in the same batch of abraded and conditioned hypocotyl segments (see Fig. 1). Gray bar, Elicitor activity; black bar, enhancement. Note that for enhancement a relative activity of 1.0 indicates no effect, whereas in the case of elicitor activity a value of 1.0 indicates the same activity as fungal elicitor. Means ± sd from three independent determinations are shown. Cutin hydrolysates from tomato, apple, and cucumber hypocotyl, as well as surface wax, were used at 100 μg mL⁻¹, whereas cucumber leaf cutin hydrolysate was used at 50 μg mL⁻¹ to allow comparison with fractions isolated by TLC.