Figure 9.

GALV-Nf cytopathology of systemically-infected grapevine leaves. (A) Virus infected cells are easily identified even under a light microscope close to small veins (X) and show different stages of plasmolysis and membrane rupture. Chloroplasts of spongy mesophyll (arrow) appear swollen, in comparison with those visible in an uninfected control leaf (B). At the ultrastructural level (C), swollen chloroplasts (Ch) show thylakoid disorganization, and numerous virus particles (V) are visible in the surrounding cytoplasm (D); mitochondria (M) are also swollen, apparently without stroma and almost devoid of cristae. An uninfected control cell is visible in (E) for comparison. Cells around small veins sometimes show incipient necrosis (F) with dense cytoplasm in which virus-like particles are still distinguishable (G). Infected parenchyma cells of small veins (H) show mitochondria with vacuolization and loss of cristae and small vesicles are sometimes present in apparently dilated ER cisternae (I). N, nucleus; P, peroxisome; Ps, plasmodesmata. Black bars = 400 nm; white bars = 100 nm, if not otherwise stated.