Molecular strategies to increase and stabilize the sucrose content of sugarcane (Saccharum officinarum L.)

Although management at the field and processing levels contributes significantly to high biomass and sugar yields, high sucrose yield remains a major objective of varietal improvement programs for sugarcane. Modern biotechnology or molecular tools can now be integrated with plant breeding protocols to manipulate genes for increased and stable sucrose content in sugarcane. This paper reviews the biochemical and physiological aspects of sucrose metabolism and the mode of action of chemical ripeners, which could provide the basis for genetic engineering to achieve increased and more stable sucrose content in sugarcane. Some strategies that use the tools of modern biotechnology are recommended: (1) increasing sucrose synthesis by overexpressing the sucrose phosphate synthase in the internode, (2) suppressing the level and thus the activity of neutral invertase in the mature internodes to stabilize sucrose content, and (3) accelerating the ripening of the immature internodes before harvesting by inserting a gene for ethylene production which can be activated by a simple chemical stimulus. Basic biochemical and physiological studies are also recommended to complement molecular tools for more efficient and effective transformation of sugarcane for enhanced and stable sucrose content. The paper also presents the latest research in this area.