Trehalose metabolism in plants

Abstract

SUMMARYTrehalose is a quantitatively important compatible solute and stress protectant in many organisms, including green algae and primitive plants. These functions have largely been replaced by sucrose in vascular plants, and trehalose metabolism has taken on new roles. Trehalose is a potential signal metabolite in plant interactions with pathogenic or symbiotic micro-organisms and herbivorous insects. It is also implicated in responses to cold and salinity, and in regulation of stomatal conductance and water-use efficiency. In plants, as in other eukaryotes and many prokaryotes, trehalose is synthesized via a phosphorylated intermediate, trehalose 6-phosphate (Tre6P). A meta-analysis revealed that the levels of Tre6P change in parallel with sucrose, which is the major product of photosynthesis and the main transport sugar in plants. We propose the existence of a bi-directional network, in which Tre6P is a signal of sucrose availability and acts to maintain sucrose concentrations within an appropriate range. Tre6P influences the relative amounts of sucrose and starch that accumulate in leaves during the day, and regulates the rate of starch degradation at night to match the demand for sucrose. Mutants in Tre6P metabolism have highly pleiotropic phenotypes, showing defects in embryogenesis, leaf growth, flowering, inflorescence branching and seed set. It has been proposed that Tre6P influences plant growth and development via inhibition of the SNF1-related protein kinase (SnRK1). However, current models conflict with some experimental data, and do not completely explain the pleiotropic phenotypes exhibited by mutants in Tre6P metabolism. Additional explanations for the diverse effects of alterations in Tre6P metabolism are discussed.

Transcriptome Profiling of Tiller Buds Provides New Insights into PhyB Regulation of Tillering and Indeterminate Growth in Sorghum

“…Sugar signaling occurs through pathways involving hexokinase, trehalose-6-phosphate/SnRK1, and TOR, and by direct effects of sugars on growth and metabolism (Rolland et al, 2006;Lunn et al, 2014;Ruan, 2014). In this study, transcriptome analysis revealed that the trehalose phosphate phosphatase TPPI-like gene was expressed at 9-fold higher levels in buds of phyB-1 at 6 DAP and 34-fold higher at 8 DAP.…”

Light Remodels Lipid Biosynthesis in Nannochloropsis gaditana by Modulating Carbon Partitioning between Organelles

“…The sugar accumulation signature in HL could negatively regulate photosynthesis and Calvin-Benson cycle gene expression (Couée et al, 2006;Supplemental Data Set S3A), as reported in several plant and cyanobacteria species when exposed to high light conditions (Pego et al, 2000;Rolland et al, 2006). In other photosynthetic organisms, sugar accumulation has also been correlated with the down-regulation of peroxisomal lipid b-oxidation (Contento et al, 2004), carotenoid biosynthesis (Ryu et al, 2004), and reactive oxygen species scavenging processes (Stoop et al, 1996;Elbein et al, 2003;Lunn et al, 2014), all phenomena also observed in this work, suggesting a possible role for sugars not only as carbon sinks but also as signaling molecules (Supplemental Note S1).…”

Alteration of plant primary metabolism in response to insect herbivory

“…Research involving both Arabidopsis and tomato genes suggested that TREHALOSE PHOSPHATE SYNTHASE11 activity regulates host defense during infestation with green peach aphid by providing a threshold level of signaling trehalose (Singh et al, 2011;Singh and Shah, 2012). However, whether plants regulate trehalose signaling through an internal pool or in response to exogenous addition from insect honeydew remains an open question (Lunn et al, 2014).…”