Plant Cytochromes CYP74 family: biochemical features, endocellular localisation, activation mechanism in plant defence and improvements for industrial applications

Not just another P450: Shown here is a model of the overall structure of CYP74C3 with the putative membrane-binding region that is required for enzyme activation. Members of the CYP74 family of cytochrome P450 enzymes are specialised in the metabolism of hydroperoxides and play an important role in oxylipin metabolism, which is one of the main defence mechanisms employed by plants. In order to respond to their rapidly changing environments, plants have evolved complex signalling pathways, which enable tight control over stress responses. Recent work has shed new light on one of these pathways that involves the different classes of plant oxylipins that are produced through the CYP74 pathway. These phytochemicals play an important role in plant defence, and can act as direct antimicrobials or as signalling molecules that inducing the expression of defence genes. The fine-tuning regulation of defence responses, which depends on the precise cross-talk among different signalling pathways, has important consequences for plant fitness and is a new, challenging area of research. In this review we focus on new data relating to the physiological significance of different phyto-oxylipins and related enzymes. Moreover, recent advances in the biotechnological production of oxylipins are also discussed.