Sucrose Accumulation in Sugar Beet: From Fodder Beet Selection to Genomic Selection

Sucrose has been known as the main form of energy transport and storage in many economically important plant species. For the past two centuries, sugar beet has been selected as a source of sweetener in human diets for its high sucrose content. Over the past decades, sugar beet breeding has achieved significant goals in the development of taproot yield and sucrose yield. There is still scope for improvement, despite the fact that the sucrose concentration of the taproot today is around 15-20% of the beet's fresh weight. Sucrose accumulation begins early in the growing season and increases linearly with time in the first half of the development, and saturation is reached in the second half. Desirable hybrids are expected to have small-cell root tissue and a rapid cell division rate as well as bearing the characteristic of high sucrose cultivars. Results of different studies have shown that sugar concentration is influenced greatly by the maternal parent under additive inheritance. The root selection for this trait at early developing programmes may be done by simple selection methods; however, improving above normal limit/percentage demands more complicated/expensive methods. The ease of molecular markers application and also linkage mapping approaches paved the way for sugar beet breeding. Beside sucrose extraction, producing sugar beets with high fructan accumulation, extracting ethanol from its glucose, and biobased materials formation from beet waste assure a promising future for this crop. The present review focuses on the advancements made in understanding sucrose accumulation in the sugar beet root.