Figure 9.

Cytochemical Localization of Wound-Inducible H₂O₂ in Mesophyll Cells of Tomato Leaves.

(A) Spongy mesophyll cells of a control leaf from an unwounded plant does not exhibit H₂O₂ in the cell walls or intercellular spaces (IS).

(B) Accumulation of H₂O₂ in the bordering cell walls of a vascular parenchyma and a spongy mesophyll cell of a wounded leaf 4 hr after wounding.

(C) Accumulation of H₂O₂ in the cell walls of two spongy mesophyll cells facing an intercellular space 4 hr after wounding of the leaf.

(D) Systemic H₂O₂ accumulation in the cell walls of two spongy mesophyll cells facing an intercellular space 4 hr after wounding of the lower leaf.

(E) Constitutive accumulation of H₂O₂ in the cell wall of a spongy mesophyll cell of a leaf from a transgenic tomato plant overexpressing prosystemin. The proteinaceous material (P) within the central vacuole corresponds to aggregates containing proteinase inhibitor proteins that constitutively accumulate in transgenic tissue.

(F) Inhibition of wound-induced H₂O₂ accumulation by DPI. Leaf samples were obtained 4 hr after wounding.

C, chloroplast; CW, cell wall; M, mitochondrion; N, nucleus; P, protein aggregates of defensive inhibitor proteins; V, central vacuole. Bar in (A), (C), (D), and (F) = 2 μm; bar in (B) and (E) = 1 μm.