From appressorium to transpressorium—Defining the morphogenetic basis of host cell invasion by the rice blast fungus

[...]we evaluate evidence suggesting that a specialised infection cell—the transpressorium—is necessary for invasive growth. First of all, a hard hydrophobic surface [6] must be recognised by M. oryzae, which requires the Pmk1 mitogen-activated protein kinase (MAPK) signalling pathway. [...]the 3-celled conidium undergoes autophagy and an iron-dependent programmed cell death process, called ferroptosis, before its contents are trafficked to the appressorium [9,10]. The initiation of autophagy requires both Pmk1 and cell cycle progression, but is also linked to starvation stress and a target of rapamycin (TOR) kinase–dependent metabolic checkpoint [11], because appressoria only develop in the absence of exogenous nutrients.