Genome Reveals When Opium Poppy Became a Painkiller
A combination of two genes over 7.8 million years ago was the first step to producing morphine and other narcotic compounds
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Opium, morphine, heroin, codeine and synthetic drugs like hydrocodone have one big thing in common: they are all derived from the opium poppy, Papaver somniferum, a pretty flower cultivated in dry climates. Leslie Nemo at LiveScience reports that researchers have analyzed the genome of the poppy, finding that a series of mutations inside the plant over 7 million years ago gave the flower its pain-killing superpower.
To investigate, an international team of researchers sequenced the 2.72 billion base pairs over 11 chromosomes that make up most of the opium poppy’s genome, according to their new study published in the journal Science. They then identified and drilled down on 15 genes that produce morphine and other related compounds. Using a technique called the “molecular clock,” they were able to tell how far back in time certain mutations took place.
The first major development occurred 110 million years ago when the poppy made an extra copy of almost its entire genome. That’s not unusual in certain types of plants. While one copy stays relatively stable, the second copy often develops interesting mutations that give the plant new characteristics. According to a press release, this duplicate genome gave the poppy the ability to produce various compounds that help ward off microbes and pests, but also attract more pollinators.
More than 7.8 million years ago, two genes for synthesizing these chemicals merged into a “megagene” called STORR, which is responsible for the first stages of morphine and codeine synthesis. Nemo reports that without the big gene, the poppy would transform precursor molecules into noscapine, a compound without any pain-killing properties.
But the STORR gene doesn’t work alone to produce morphine—it appears that a team of genes assist in the process. When, why and how the STORR gene linked up with others to produce the potent painkiller is a mystery that the researchers hope to investigate further in future studies.
For now, however, having the poppy genome in hand is a big deal for drug manufacturers. Ryan Mandelbaum at Gizmodo reports that though the opioid epidemic makes it seem like the world is awash in the drugs, that’s not the case. Many regions, especially non-western nations, face morphine and narcotic shortages in treating patients in medical clinics, so finding cheaper, faster ways to produce the drugs is key.
Currently, growing opium poppies is still the best way to produce these compounds, which happens on farms in a 4,500-mile arc from Turkey to Burma. Having the poppy genome sequence handy could allow researchers to breed new strains of poppies that grow better in agricultural fields. “Like every other species of plants, poppies are subject to disease by mildew,” Graham tells Katherine Gammon at Inside Science. “In the future, we could get higher yields of the drugs in a controlled way through disease-resistant crops.”