The role of trehalose 6-phosphate in regulation of primary and lateral root development

• Applicant: Dr. Franziska Fichtner
• Subject Area: Plant Physiology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 515360083

Plants need to sense their carbon supply and demand in order to regulate their metabolism and provide cues for development and growth of new organs. Trehalose 6-phosphate (Tre6P) is a signal metabolite that regulates sucrose metabolism and is essential for normal growth and development. Developmental transitions, such as flowering and shoot/root branching commit the plant to new growth that will consume sucrose and other nutrients. We hypothesize that Tre6P signalling is important to regulate growth to balance the supply and demand of nutrients. Tre6P is synthesized by TREHALOSE-6-PHOSPHATE SYTHASE (TPS) and dephosphorylated by TREHALOSE-6-PHOSPHATE PHOSPHATASE. In Arabidopsis, TPS1 is responsible for Tre6P synthesis in post-embryonic tissues, is mainly expressed in the vasculature of shoots and roots, a highly strategic site for systemic signalling, and is known to be a critical element in the nexus between sucrose and Tre6P. Most studies have focussed on establishing the function of Tre6P in shoots. We previously demonstrated that changing Tre6P levels in the vasculature modulated flowering and branching, and showed it does so by interacting with photoperiodic signalling as well as by altering sucrose allocation. In addition to this systemic signalling pathways, Tre6P also has a local function in axillary buds to modulate shoot architecture. The function of Tre6P in roots, however, is still unclear. Our unpublished data shows that primary root and lateral root growth is strongly affected by Tre6P levels. Tre6P acts thereby locally in the roots and potentially systemically in the shoot and interacts with known hormonal and nutrient signalling pathways to alter root architecture. This proposal will uncover where Tre6P synthesis occurs and how Tre6P acts during primary and lateral root development. We will use established lines with alterations in Tre6P in the vasculature to investigate the cause of the altered root structure by Tre6P using grafting approaches combined with phenotypic and metabolic analyses. Further root-specific inducible Tre6P accumulation lines will be generated and analysed with regards to their developmental and metabolic phenotypes. Targeted and untargeted approaches will be combined to identify key players in the Tre6P signalling network and aid at placing Tre6P in the established regulatory network controlling root growth. Finally, we will also use soil-based phenotyping assays comparing root and shoot trade-offs in lines with alterations in Tre6P. This project will deepen our knowledge on Tre6P signalling in roots which have been greatly neglected in Tre6P research to date, and establish whether Tre6P acts as both a systemic and local signal of sucrose in the root. Such knowledge will underpin future efforts to improve the growth and productivity of crop plants by modulating Tre6P signalling.

• DFG Programme: Research Grants
• International Connection: Australia
• Cooperation Partner: Dr. Christine Beveridge