Abstract

To cause disease, many fungal pathogens develop specialised structures to rupture the tough outer layers of their plant or animal hosts. These infection cells, called appressoria, have been extensively studied in many fungal species [1]. However, once inside host tissue, pathogens must also invade new cells and traverse host cell junctions. How they do this has received much less attention, but recent evidence from the rice blast fungus suggests that cell invasion within a host plant may also require the development of a specialised infection structure. Here, we compare the developmental biology of invasive growth during different stages of plant infection by the rice blast fungus. We identify the remarkable parallels between the biology of appressorium development and cell-to-cell movement. Finally, we evaluate evidence suggesting that a specialised infection cell—the transpressorium—is necessary for invasive growth.