Carrots are among a few crops storing free sugars (sucrose, fructose and glucose) in their roots, not starch. The sugar types are controlled by a single dominant gene Rs (for reducing sugar). In this PhD dissertation turned book, the author described the use of molecular technology to study the genes for several sugar metabolism enzymes in two near-isogenic carrot lines, Rs/Rs and rs/rs, which accumulate glucose plus fructose and sucrose, respectively. Using molecular approaches, the author reveals the candidate gene responsible for the sugar type accumulation in mature carrot roots. In addition, the author also described how to further deploy a strategy to rapidly identify and predict the sugar types in the mature carrot roots from early-stage seedlings by a simple polymerase chain reaction (PCR) using primers designed from the DNA sequences of the mutant (rs) and the wild type (Rs) alleles. Research on genetic transformation of carrot was also performed and discussed. This bookwill interest biology researchers, students and an audience interested in learning how to use modern molecular technology to study genes associated with specific traits.