Figure 6.

Treatment of tobacco leaves with laminarin causes no tissue damage or cell death. Representative data of three independent experiments are shown. A, Tobacco leaves were infiltrated (zones delineated with black pencil) with 200 μL of 200 μg mL⁻¹ laminarin, water (Control), or with 50 nm of β-megaspermin (β-meg.), a necrosis-inducing proteinaceous elicitor used as a positive control. The photographs were taken 5 d after infiltration. B, Microscopic examination (15× magnification) after trypan blue staining of the corresponding infiltrated zones in A. The microphotographs are cropped to show a portion of an infiltrated necrotic zone (bright blue) and a portion of the surrounding zone.