Papaver somniferum L. taxonomy, uses and new insight in poppy alkaloid pathways

Since ancient times, opium poppy (Papaver somniferum L.) is known for its medicinal properties, related to its secondary metabolite content. Its most important secondary metabolites, called benzylisoquinoline alkaloids (BIAs), are still essential in pharmaceutical field. Few of them, like morphine, have specific clinical application but also effects on CNS. Not all poppy cultivars are able to biosynthesize morphine in high amount, making this plant useful for other purposes like food uses. For this reason it is crucial to deeply understand the origin of poppy, its possible use and have a deep knowledge of the BIA biosynthesis. These aspects are crucial for the final use of P. somniferum. This review aims to summarize the state-of-the-art on its taxonomy and origin beside its uses and BIA biosynthetic pathways, its most important metabolites. The review focuses on conflicting or unsolved questions about enzymatic localization, role of different plant organs in the biosynthesis, and storage and external conditions that influence the alkaloid production, highlighting the significant involvement of transcription factors. Behind this review, there is the firm belief that only a deep knowledge of alkaloid biosynthetic processes could lead to the characterization of undefined step and to the development of engineering cultivars optimizing the potential uses of P. somniferum. The goal is answer in more sustainable way to ever-increasing worldwide request of such products, in particular morphine and derivates, obtaining high morphine content cultivars useful for pharmaceutical market or no morphine producing cultivars appreciated as food. Devising cultivars with different BIA content could lead to decrease, or even avoid, illicit use and illegal extraction, confining only low alkaloid content cultivars to consumers market.