Biochemical Society Transactions vol:33 pages:276-279
Biochem. Soc. Focussed Meeting: Nutrient sensing in eukaryotic cells location:Cirencester, UK date:25-29 September 2004
Plants sense and respond to changes in carbon and nitrogen metabolites during development and growth
according to the internal needs of their metabolism. Sugar-sensing allows plants to switch off photosynthesis
when carbohydrates are abundant. These processes involve regulation of gene and protein activity to allow
plants the efficient use of energy storage. Besides being a key element in carbon metabolism, glucose
(Glc) has unravelled as a primary messenger in signal transduction. It has been proved that hexokinase
(HXK) is a Glc sensor. An unusual disaccharide named trehalose is present in very low levels in most plants
except for the desiccation-tolerant plants known as ‘resurrection’ plants where trehalose functions as an
osmoprotectant. We have shown that overexpression of the Arabidopsis trehalose-6-phosphate synthase
gene (AtTPS1) in Arabidopsis promotes trehalose and trehalose-6-phosphate (T6P) accumulation. Seedlings
expressing AtTPS1 displayed a Glc-insensitive phenotype. Transgenic lines germinated normally on Glc, in
contrast to wild-type seedlings showing growth retardation and absence of chlorophyll and root elongation.
Gene-expression analysis in transgenic plants showed up-regulation of several genes involved in sugar
signalling and metabolism. These data suggest that AtTPS1 and accordingly T6P and trehalose play an
important role in the regulation of Glc sensing and signalling genes during plant development.