A hypothesis of sector switching.

First, recognition of MAMPs leads to activation of the EMT sectors (A), which then activates the SA sector (B) [30]. If pathogen effectors perturb the EMT sectors, the inhibition of the SA sector by the EMT sectors becomes negligible, and the SA sector becomes highly activated, including signal amplification involving positive feedback [70], and deploys a potent defense response (C). If pathogen effectors perturb the SA sector, the inhibition of the EMT sectors by the SA sector becomes negligible, and the EMT sectors become highly activated and deploy a strong defense response (D). Note that the EMT sectors and the SA sector are not highly activated simultaneously.