Increasing sugar content is a primary objective of sugarcane improvement programs worldwide. Despite decades of breeding, sugar content has remained stagnant in new varieties in most sugar industries globally (FAO, 2012). Sugar yield improvement to date has been achieved largely through increased cane yield. Sugar accumulation in sugarcane is well below the theoretical physiological limits (Moore, 2005) but has proven very difficult to improve through breeding or molecular approaches (Geoff Inman-Bamber, 2013). From a whole of industry perspective, the benefit of improving commercial cane sugar is estimated to be up to 1.8 times greater than an equivalent proportional improvement in cane yield (Jackson, 2005).
Dr Luguang Wu and his team at the University of Queensland (UQ) have successfully discovered and manipulated a key endogenous sucrose-metabolism gene to deliver a 15-25% increase in sugar levels in transgenic sugarcane compared to wild type. The phenotype has remained true under various environmental conditions and growth stages that have been examined to date: water deficit, excess water, varying light conditions, young plants, mature plants, various nutrient conditions. This high-sucrose phenotype has been stable across three generations under glasshouse conditions and experiments are now underway to assess performance in the field. Increased sugar content is a major industrial target with the allure of higher returns on fixed capital costs (cane production, milling and initial refining) and the sucrose yield promoter technology offers an exciting opportunity to deliver this to industry.