How the poppy got its pain-relieving powers
Duplicated genes helped the plants evolve to make molecules like morphine
A draft of the poppy’s genetic instruction book is providing clues to how the plant evolved to produce molecules such as morphine.
Scientists pieced together the genome of the opium poppy (Papaver somniferum). Then, they identified a cluster of 15 close-together genes that help the plant synthesize a group of chemically related compounds that includes powerful painkillers like morphine as well as other molecules with potential medical properties (SN: 6/10/17, p. 22).
A group of genes that help poppy plants produce some of these molecules, collectively known as benzylisoquinoline alkaloids, have been clustered together for tens of millions of years, researchers report online August 30 in Science. But the plant’s morphine production evolved more recently. Around 7.8 million years ago, the plant copied its entire genome. Some of the resulting surplus genes evolved new roles helping poppies produce morphine, because the plant already had at least one other copy of those genes carrying out their original jobs.
It wasn’t a one-step process, though. An even earlier gene duplication event caused two genes to fuse into one. That hybrid gene is responsible for a key shape-shift in alkaloid precursors, directing those molecules down the chemical pathway toward morphinelike compounds instead of other benzylisoquinoline alkaloids (SN Online: 6/25/15).