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Opium poppy “learned” to produce morphine 8 million years ago

Opium poppy (Papaver somniferum) . Illustration from Atlas of Medicinal Plants Köhler.
Biodiversity Heritage Library

Geneticists followed the evolution of the opium poppy and found that the plant “learned” to produce the alkaloid morphine relatively recently, about eight million years ago, according  to an article published in  Science .

From the immature boxes of sleeping pills (or opium) poppies ( Papaver somniferum) , condensed opium juice is obtained. It contains about 20 alkaloids, including morphine, papaverine and codeine, which are used as pain medications. These substances are still obtained from poppies, since it is difficult and expensive to synthesize them chemically or biologically.

In the opium poppy, morphine is formed from dopamine and the thebaline alkaloid, as an intermediate. The key enzymes in the synthesis of morphine are cytochromes P450 and oxidoreductase, which work “in pairs”. Their genes form a single locus, STORR, which was formed as a result of the fusion of parts of the genome.

Alternatively, alkaloid noscapine (or narcotin) is formed from dopamine, which is used as an antitussive agent. The biosynthesis of noscapine occurs with the participation of a number of enzymes, which in the genome of the poppy form a cluster consisting of 10 genes.

British, Chinese and Australian scientists led by Ian Graham of York University sequenced the opium poppy gene and found out how the metabolism of alkaloids evolved.

The genome of the poppy contains 2.72 billion base pairs. For comparison, the human genome has about 3.1 billion pairs. Researchers compared the genome of opium poppy to the genomes of 11 flowering plants and found that the division of the next of kin – opium poppy from the family of poppies and catchment blue ( Aquilegia coerulea ) from the family of buttercups – occurred about 110 million years ago. Soon after this, the genome of the opium poppy was rebuilt – full-genomic duplication. And about 7.8 million years ago, there was another full-genomic duplication. Duplication refers to the doubling of individual genes, chromosome regions or, as in this case, the entire genome. As a result, new genes appear, since after doubling copies of genes begin to develop independently of each other and they accumulate different mutations.

Scientists have established that a cluster of genes responsible for the synthesis of noscapine, appeared as a result of older duplication, about 110 million years ago. And the locus STORR, necessary for the development of morphine, appeared much later, as a result of the second rearrangement of the genome. A number of genes responsible for the synthesis of the intermediate for the production of morphine, thebaine, was formed earlier than eight million years ago, before the second full-genomic duplication.”Biochemists for decades tried to figure out how the evolution of plants took place, as a result of which they were able to produce a huge number of chemicals. With the help of a high-quality assembly of the genome, we were able to decipher what was happening in the genome of the opium poppy, “explains  Graham. “At the same time, this study will provide the basis for developing tools for molecular plant breeding. They can be used for reliable and cheap production of anesthetics not only in developed, but also in developing countries. ”

With the development of sequencing methods, scientists are becoming increasingly able to obtain high-quality genomes. So, most recently, the most detailed genome of wheat was published , and shortly before that, researchers followed the evolution of the domestication of grapes and the history of roses.

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