Process of infection and colonization of Pseudocercospora kaki in persimmon leaves

Abstract

AbstractCercosporiosis, caused by Pseudocercospora kaki, is the major foliar disease in persimmon crops. Despite the importance of the disease, we have little information about the interaction of this pathogen with persimmon leaf tissues. Therefore, to elucidate the infection and colonization process in these pathosystem, we investigated this interaction using light and scanning electron microscopy. Forty‐eight hours after inoculation, the germ tubes produced from conidia and entered the leaf tissue only through the stomata. The lesions formed were limited to the areolas of leaf venation. The accumulation of phenolic and lipophilic compounds, and parietal thickening by increased pectin content in the cells of the bundle sheath, restricted the advance of the fungus. During the colonization process, hyphae produced vesicles in the intercellular spaces of the mesophyll. These vesicles in contact with the cell wall of the chlorophyll parenchyma caused parietal changes. Pathogen sporulation occurred only on the adaxial surface of the leaves and produced sporodochium exposed on the outer leaf surface. This study showed how P. kaki penetrates in the persimmon leaves, and the process of colonization, with epidermal alterations and the lysis and collapse of mesophyll cells in the lesioned area, and finally, the formation of reproduction structures of the pathogen.