They compared a number of varieties of roses, some exuding lots of scent and others producing none. They found that a protein called nudix hydrolase RhNUDX1 in the cytoplasm of petal cells was present in scent-producing flowers and absent in those with no smell. It turns out that the gene responsible for building the protein was turned on in scented flowers and turned off in the others. The group was able to conclude that RhNUDX1 encodes a key part of the pathway that produces the small volatile molecules, called monoterpenes, which make up 70 percent of some rose cultivars’ smell.
“We saw that every time this gene was expressed highly, the rose was making these monoterpene molecules,” she said. “We were really surprised about this.”
Along with the possibility of modifying the plant to make the smell-producing gene work again, the team’s work can also be used as a marker for breeders to tell them which cultivars will produce scented roses before they even grow flower buds.