Ultrastructural changes of mesophyll cells in peach leaves infected by <i>Taphrina deformans</i> (Berk/Tul)

Taphrina deformans (Berk/Tul) is a causal agent of peach leaf curl that causes severe deformation of leaves and, in some cases, affects plant fruits and shoots, thereby exerting an adverse effect on tree yield and vitality. It has the potential to cause epidemics. The present study indicated ultrastructural alterations in the mesophyll cells of peach leaves, Fayette cultivar, in response to infection by T. deformans. Pathogen-induced hypertrophy and hyperplasia are associated with the unbalanced growth of the infected cells. Changes in the shape of the mesophyll cells from cylindrically oval to isodiametric were found. A strong destruction of the cell compartments was established in a thin parietal cytoplasm. The degradation of chloroplast membrane structures was significant. The regular shape of the chloroplasts was lost with the appearance of concavities. The middle lamella was expanded and exhibited the presence of T. deformans hyphae provoking those alterations. They contacted the cell wall but did not entirely disrupt it. This study confirms and complements the ultrastructural picture of peach leaf curl in the dynamic plant-host system.