Lipases and the biosynthesis of free oxylipins in plants.

The production of free oxylipins in plants is exquisitely controlled by cellular mechanisms that respond to environmental factors such as mechanical damage, insect herbivory and pathogen infection. One of the main targets of these cellular mechanisms are glycerolipases class A (GLA); acyl-hydrolyzing enzymes that upon their biochemical activation release unsaturated fatty acids or acylated oxylipins from glycerolipids. Recent studies performed in the wild tobacco species Nicotiana attenuata have started to reveal the complexity and specificity of GLA-regulated free oxylipin production. I present a model in which individual GLA lipases associate with individual lipoxygenases (LOX) in chloroplast membranes and envelope to define the initial committed steps of distinct oxylipin biosynthesis pathways. The unravelling of the mechanisms that activate GLAs and LOXs at the biochemical level and that control the interaction between these enzymes and their association with membranes will prove to be fundamental to understand how plants control free oxylipin biogenesis.