A rose by any other name would smell as sweet, as Shakespeare wrote, but erase just one little molecule in their flowers and you’d be lucky to catch a whiff of anything at all. In recent decades, commercial gardeners have bred roses that grow in different colors, are more insect-resistant, and have a longer vase life. But that manipulation has a trade-off: more visually appealing flowers often lose their strong aromatic fragrances.
What do roses need to make their pleasant odors, and more importantly, how do we get them back? A new study published Monday in PNAS identified a key enzyme called farnesyl diphosphate (FPP) synthase, crucial for driving the reaction that creates a rose’s fresh and floral scent. The findings could help with finding a way to create more mesmerizing and beautiful roses.
A chemical called geraniol is responsible for the sweet scent we associate with roses. Roses make the compound through a chemical reaction that involves FPP synthase plus several other enzymes. The process involves NUDX1 hydrolase, an enzyme found in the liquid interior of plant cells, or cytosol, that make up the rose petals. To create a strong and sweet aroma, flowers need a ton of NUDX1 hydrolase activity. This is only possible when there is enough of a binding molecule called geranyl diphosphate (GPP). GPP glues to the enzyme and propels it into action.
But in order for this process to work, the binding molecule needs to be nearby. This isn’t the case for roses. Senior author Benoît Boachon, a plant biochemist at the French National Centre for Scientific Research, says most plants keep GGP and NUDX1 hydrolase in another area called the plastids. These organelles act as key sites for photosynthesis. This motivated Boachon and his colleagues to figure out where roses get the GPP to make geraniol. He hypothesizes that GPP could have some mechanism transporting it from the plasmid to the cytosol, or there’s another pathway for the flower to generate its own supply of GPP.
To solve the plant mystery, the study authors studied the biochemical reactions that take place in a variety of pink roses called Old Blush. They isolated different plant parts and shut down chemical pathways involved with the creation or release of geraniol. If the altered roses no longer made geraniol, or the plants produced it in low amounts, that was a major clue to the scientists—they’d found a pathway that plays a role in supplying GPP. On the other hand, the team could rule out a process if geraniol continued to be made at normal levels.
Source : Popsci