ULTRASTRUCTURAL ALTERATIONS IN OAK LEAVES PARASITIZED BY TAPHRINA CAERULESCENS

Leaves of Quercus velutina Lam. parasitized by Taphrina caerulescens (Desm.) Tulanse were examined with the electron microscope to ascertain cellular aberrations that were induced by the fungus. Major changes were most apparent in the lower epidermis, where cellular divisions and enlargement were common, the cell walls becoming irregularly thickened. Many of the ultrastructural features of the diseased cells resembled those of meristematic cells; the absence of a large central vacuole, a disproportionately large nucleus, and an abundance of cytoplasmic organelles. Chloroplasts with large amounts of starch were also routinely observed.