Abstract
Presence of epidermal cell was essential for the induction of self-defense reaction of citrus plants when inoculated with Diaporthe citri (Faw.) Wolf. If the epidermis was removed from the plant, the self-defense reaction did not occur even if mesophyll was inoculated with the fungus or wounded with a knife mechanically. This suggests that a inducer of self-defense reaction exists in the epidermal cell, and is activated when those cells are damaged. When the self-defense reaction did not induce by penetration with D. citri due to removal of epidermis, fungus spread inside the tissues, and pycnidia and spore-horn were formed.
