Effects of silverleaf infection on ultrastructure of foliage ofPrunus,Rosa, andPopulus

Abstract

Abstract Foliage of peach, rose, and poplar, silvered as a result of stem infection Chondrostereum purpureum, was examined by both light and electron microscopy. Silvered leaves had fewer palisade cells which were more loosely arranged than in healthy leaves. Also, the epidermis became detached from palisade cells. Both palisade and spongy mesophyll cells were highly vacuolate, and moribund chloroplasts were packed with starch granules. Cells micro-organelles showed little ultrastructural change apart from the chloroplasts which become more electron dense, and the thylakoids and intergranal lamellae which became disorganised. Leaf area, transpiration, and stomatal conductance decreased significantly as the intensity of leaf-silvering increased. Stomata of severely-silvered leaves remained closed. Affected foliage possibly died of starvation as a result of severe water stress arising from physical occlusion of vessels in conjunction with possible toxin action in the leaves.