Roles of Sugars in Controlling Flowering Time

Flowering time is influenced by environmental factors such as photosynthesis, temperature, nutrition, and water. The main products of photosynthesis are sugars that are mobilized to sink tissues to support plant growth and differentiation. They also function as signals to control various types of metabolism and developmental processes. One of the most important transitions in the plant life cycle is from the vegetative to reproductive phase. During that transition, sucrose levels rise rapidly but transiently in the phloem and shoot apexes. For several species, the addition of exogenous sucrose promotes flowering, possibly by acting as a main signal. Although other sugars, including glucose, also appear to be involved in this transition, evidence for their roles in flowering is limited. In Arabidopsis thaliana, trehalose-6-phosphate serves as a signal to induce flowering. However, its roles in other plants have not been reported. Sucrose seems to function primarily in the leaf phloem to enhance the generation of florigens such as Flowering Locus T (FT) while trehalose-6-phosphate functions in the shoot apical meristem to promote the flowering signal pathway downstream of those florigens.