Infection process and host responses to Elsinoë ampelina, the causal organism of grapevine anthracnose

Grape anthracnose, caused by Elsinoe ampelina, is an important fungal disease during grape production. Little is known about the interactions of grape-E.ampelina compared with other grapevine fungal diseases. This study used potted seedlings of Vitis vinifera ‘ Red Globe’ and E. ampelina to investigate their interactions under greenhouse conditions. The infection process of E. ampelina in the young leaves of grape was observed from 0 to 6 days post-inoculation (dpi) under microscope. Results showed that the first symptom on grape leaves were observed at 3 dpi. The rates of conidialgermination on grape leaves were 23.4, 73.2, and 85.6% at 1, 2, and 3 dpi, respectively. Early penetration occurred in the epidermal cells with or without forming appressoria at 2 dpi. E. ampelina enlarged in intercellular spaces at 2–3 dpi and began to enter intracellular spaces from 3 dpi. New conidia were produced in acervuli on the leaf surface from 6 dpi. The ultrastructural observation revealed defense responses in infected host cells, including collapse of cell walls and chloroplasts, changes in the number of mitochondria, plasmolysis, and cell death. Overall, these results provide a detailed understanding of the grape-E.ampelina interaction and theoretical bases for infection pathway of grape anthracnose.