Understanding how plants integrate metabolic signals with developmental processes is crucial for uncovering the mechanisms underlying their growth and adaptation.

Trehalose 6-phosphate (Tre6P) is an important signalling metabolite in plants with influence over many developmental and metabolic processes. It has been demonstrated that Tre6P is both a sucrose-specific signal and a negative feedback regulator or sucrose levels. This means that Tre6P levels are not only responsive to changes in sucrose supply and act as a signal for sucrose availability, but also that the levels of Tre6P are sensed by the plant to modulate sucrose levels in return. This homeostatic function of Tre6P is thereby somewhat analogous to the insulin-glucagon system that regulates blood glucose content in animals and humans. As sucrose is the main transport sugar in most land plants, Tre6P is a key signal that helps plants to use their carbon resources in an efficient manner.

Tre6P is thus involved in connecting plant metabolism and development with carbon availability.

Tre6P is essential in the model plant Arabidopsis thaliana, as mutations in the main Tre6P synthase (TREHALOSE-6-PHOSPHATE SYNTHASE1) are embryo lethal in Arabidopsis plants. Using tagged version of TPS1, we demonstrated that Tre6P synthesis is predominantly located in meristematic tissues like the shoot apical and axillary meristems, as well as in the vasculature of shoots and roots.

Altering Tre6P levels results in a reprogramming of metabolism and many phenotypic alterations in plants, including changes in flowering time, shoot branching, and root development. Tre6P thereby acts locally in sink tissues, so sugar consumers, and source tissues, so net sugar producers, as well as systemically in the vasculature. Especially its systemic role in the vasculature suggests that Tre6P might be a new phytohormone-like signalling metabolite.

Land plants evolved from streptophyte algae, a lineage of green algae, around 500 million years ago. Beyond its role as a sugar signalling molecule, Tre6P is also the intermediate of trehalose biosynthesis. Trehalose, a non-reducing disaccharide, functions as an osmolyte and stress protectant and therefore may have played a crucial role in the transition from aquatic to terrestrial life. However, the specific contributions of trehalose and Tre6P to land plant evolution remain unclear. Sugar signalling components, including Tre6P-related genes, are present in all chloroplastida and have diversified in land plants. We are currently investigating conserved and unique signalling pathways in all green plants using key representative species of the green lineage and combining experimental and modelling approaches. 

My vision is to understand the fundamental mechanisms that link plant metabolism to plant growth. 

If you are keen to explore that vision and are interested in joining the Tre6P Team, then get in contact! 

Publications Franziska Fichtner

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