A blue rose is mythical, legendary, never found in nature without human artifice. The notion of such a flower has appeared in numerous stories and in popular media.
There's an episode of the Smurfs where Smurfette sacrificed her blue skin color to see a blue rose. Unfortunately her skin turned white and exuded the smell of a rose which earned the attention of bugs. She broke the deal with Mother Nature, lost the blue rose but regained some peace. Thief of Baghdad starring Steve Reeves and directed by Ray Harryhausen was centered around the quest for a mystical blue rose to cure a sick princess. Also there's an ancient Chinese folktale about the emperor's daughter demanding a blue rose as a requirement for a husband, the blue rose symbolizing honesty. She passes on several gentlemen of noble heritage who present her with fakes or representations of a blue rose. A simple farmer presents her with a mere white rose which turned blue when he held it under the rays of a sunset shining through the court's blue stained glass windows. They all lived happily ever after.
Until recently these roses only existed in stories or through the deft application of dye to a white rose's petals and Photoshop. Now through the magic of genetic engineering there will be a chimerical blue rose.
Scientists researching how the liver breaks down drugs discovered an enzyme which turned bacteria blue. One thing lead to another and they had the bright idea to patent the process to make money and blue roses. Keep an eye out for them by next Mother's Day.