Instead of filling up your car with gasoline, imagine using the sap from a tree. One Colorado biologist said the idea may be possible thanks to a special "diesel tree" that grows in Central and South America.The trunk of the copaiba tree produces a resin that is used for medicine, but Dr. Chhandak Basu, assistant biological professor at the University of Northern Colorado, said the plant has some serious potential as a biofuel.The plant comes with a few problems. It only grows in the tropics and it grows too slowly to efficiently make the resin into a fuel for your car. After five years of research, Basu has a solution."The goal is that if we can identify the genes that may be responsible for the diesel-like fuel production, we can engineer plants or algae with those genes," he said.Those plants and algae could be used to mass produce the resin right here in Colorado.Basu said using non-food crops would make the biofuel an even better alternative to ethanol, which is produced from corn."I am from a developing country," he said. "I was born in India. I really don't want to use food crops that could be used to feed the hungry people in developing countries."The biggest hurdle now is mapping all of the diesel tree's genes. Basu has completed 800, but estimates there are thousands more. It's painstaking work, but he said not as painful as the alternative."Well, last summer the price of gas was $4 a gallon," he said.The Colorado Office of Economic Development awarded Basu a $50,000 grant for his research and UNC matched the grant. He's also working with Western Energy Partners in Tulsa, Okla. to apply for additional funding from the federal government. He said he hopes to have the first genetically modified plants ready in two to three years.