When a fungal pathogen lands on a plant leaf, the most obvious ob- stacle it faces is how to gain en- try to the underlying tissue. Unlike bacte- ria, which have to circumvent the problem by locating stomata (ores in the plant epi- dermis), wounds, or other natural open- ings, many fungal species can rupture the cuticle (the tough outer layer of a plant) directly (1). How they do so remains con- troversial (2). In the case of some fungi, enzymatic action is clearly visible at the point of infection, suggesting that the plant cuticle is dissolved ahead of the in- fecting pathogen (1).
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