Focal effector accumulation in a biotrophic interface at the primary invasion sites of Colletotrichum orbiculare in multiple susceptible plants.

We identified virulence-related effectors of a hemibiotrophic fungal pathogen Colletotrichum orbiculare, and found that a novel interface was generated by a biotrophic interaction between C. orbiculare and the host cucumber, in which the effectors secreted from the pathogen accumulated preferentially. The interface was located around the biotrophic primary hyphal neck. Here, we showed that C. orbiculare also developed this interface in a biotrophic interaction with melon, which belongs to Cucurbitaceae. Furthermore, C. orbiculare developed interface in the interaction with a susceptible plant, Nicotiana benthamiana, which is distantly related to Cucurbitaceae, suggesting that the spatial regulation strategy for effectors in C. orbiculare is not specific to cucumber; rather, it is conserved among the various plants that are susceptible to this pathogen.