PAD4, PHYTOALEXIN DEFICIENT 4, is a plant immunity signaling component that interacts with EDS1. Their coupled activity helps connect immune recognition to downstream responses; PAD4 is not itself the generic name of a pathogen-recognition receptor.
Comparative analyses found repeated joint losses of the EDS1-PAD4 pathway and associated genes in several plant lineages. This makes pathway composition an evolutionary question: absence of one component can be informative about the others.[ref]
EDS1 and PAD4 pathway-loss study by Erin L. Baggs and others. Abstract, lineage-associated losses
New to topics? Read the docs here!