Trehalose-6-phosphate and sucrose – A tale of two sugars

Wed 6 April 2016 12:30-13:30 CSIRO Black Mountain B1 Lecture Theatre:

John Lunn (Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany).

In the last 15 years, trehalose 6-phosphate (Tre6P) has been recognised as an essential signal metabolite in plants, with influence on growth and development that rivals any other signalling molecule, including the major phytohormones. Tre6P is an intermediate in the synthesis of trehalose, a very minor disaccharide sugar in plants. Mutants with altered Tre6P levels show severe defects in germination, leaf growth, stomatal regulation, flowering, shoot architecture and embryogenesis. Tre6P closely tracks diurnal and externally imposed fluctuations in the levels of sucrose, which is a major product of photosynthesis and the most common transport sugar in plants, and the main source of carbon and energy for growing sink organs. We propose that Tre6P functions as both a signal and negative feedback regulator of sucrose levels, helping to maintain intracellular sucrose concentrations within an optimal range. This function can be compared with the insulin-glucagon system for regulating blood glucose levels in animals. In leaves, Tre6P regulates photoassimilate partitioning to sucrose during the day and the remobilization of transitory starch reserves to sucrose at night, linking both of these to demand for sucrose from sink organs. In meristems and other growing tissues, Tre6P signals the availability of sucrose for growth, influencing developmental decisions and the fate of imported sucrose. The intertwined relationship between sucrose and Tre6P is captured in the sucrose-Tre6P nexus concept. This model helps us to understand how Tre6P exerts such a profound influence on plant growth and development, and provides a framework for engineering Tre6P metabolism for crop improvement.

Speaker bio

John Lunn – CV

1982-1985       BA in Natural Sciences, University of Cambridge, UK

1985-1988       PhD in Plant Science, University of Cambridge, UK

1989-1990       Postdoc, CNRS/Rhône-Poulenc Agrochemie, Lyon, France

1991-1992       Postdoc, John Innes Centre, Norwich, UK

1992-2002       CSIRO Plant Industry, Canberra, Australia

2002-present   Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany

Current position: Principal Investigator

Other information: Associate editor of the Journal of Experimental Botany

elected Ombudsman for scientific ethics at the Max Planck Institute