RNA interference can turn off morphine production in poppies, according to a group from the Commonwealth Scientific and Industrial Research Organization (CSIRO) Plant Industry in Canberra, Australia. The finding could have industrial applications.1 "This approach makes it possible to force accumulation of other interesting molecules," says CSIRO's Philip Larkin.
While the morphine production pathway is largely known, researchers understand little about what regulates the accumulation of morphine and its intermediates in poppies. Larkin and colleagues used RNAi to silence codeinone reductase (COR), the penultimate enzyme in morphine biosynthesis. "When COR was silenced, the alkaloid which accumulates was not the immediate precursor to the silenced enzyme," notes Larkin. Opium poppies usually demonstrate an alkaloid profile of morphine, codeine, oripavine, and thebaine. The 18 transgenic poppies produced by the Australian group instead displayed the nonnarcotic alkaloid S-reticuline, which lies seven enzyme steps upstream of COR.
"This is truly surprising...