Sugarcane sucrose metabolism: scope for molecular manipulation

Improvement of the sucrose content of commercial sugarcane by conventional breeding has reached a plateau, primarily due to the narrow gene pool, and the potential to introduce novel genes or manipulate native genes to influe nce metabolism may have significant application. This review reports on pro gress in developing new, and optimising existing, transformation processes for sugarcane, and confirms that the requisite molecular tools for modifyin g sugarcane metabolism are as yet poorly developed when compared with those currently being applied to dicotyledonous model and crop species. Drawing from the considerable base of biochemical research into sucrose metabolism in sugarcane, a number of target steps for metabolic manipulation are revie wed. Specifically, we review current research into the physiological and bi ochemical elucidation of the key processes of sucrose synthesis, transport and cleavage. Given the focus of this review on molecular manipulation, par ticular emphasis is placed on the status of research into the isolation of genes encoding the key enzymes and transporters in the sucrose accumulation process.