No synthetic rubber yet matches natural rubber's resilience and strength. Moreover, synthetic rubber's price is tied to that of oil, from which it is made. Trees traditionally used for rubber, though, grow slowly and must be spaced widely or risk leaf blight, making it extremely difficult to increase production. Thus, a smaller rubber-producing leaf plant has appeal. One possibility is guayule, a desert shrub that produces rubber free of allergenic proteins that is useful in such products as rubber gloves. Desert plants, however, mature slowly-guayule takes two years. Another promising rubber source is Taraxacum kok-saghyz (TKS), a Russian dandelion, a robust, fast-growing plant that can be pulled up for processing and resown easily, potentially yielding two harvests a year. To make TKS usable, German scientist Christian Schulze Gronover is investigating the enzyme, polyphenol oxidase (PPO), that makes TKS's rubber sap coagulate. Coagulation benefits the plant; that's why rubber exists: it evolved to gum up herbivorous insects' mouths. Human users, however, want to delay coagulation to facilitate rubber extraction, so Schulze Gronover developed a technique called RNA interference. This intercepts and destroys the molecular messengers carrying instructions from the PPO gene to make the enzyme. Ultimately, if this approach can be combined with bioengineering leading to higher-rubber-yielding TKS plants, the rubber industry's fortunes will no longer be so closely tied to the price of oil.