Phospholipases in action during plant defense signaling

Eukaryotic organisms rely on intricate signaling networks to connect recognition of microbes with the activation of efficient defense reactions. Accumulating evidence indicates that phospholipids are more than mere structural components of biological membranes. Indeed, phospholipid-based signal transduction is widely used in plant cells to relay perception of extracellular signals. Upon perception of the invading microbe, several phospholipid hydrolyzing enzymes are activated that contribute to the establishment of an appropriate defense response. Activation of phospholipases is at the origin of the production of important defense signaling molecules, such as oxylipins and jasmonates, as well as the potent second messenger phosphatidic acid (PA), which has been shown to modulate the activity of a variety of proteins involved in defense signaling. Here, we provide an overview of recent reports describing the different plant phospholipase pathways that are activated during the establishment of plant defense reactions in response to pathogen attack.