The sucrose-trehalose 6-phosphate nexus is conserved in flowering plants with different phloem loading and carbon...

Trehalose 6-phosphate (Tre6P) is a signalling metabolite that maintains sucrose homeostasis and links plant growth and development to the availability of sucrose. Most of our knowledge of the nexus between Tre6P and sucrose comes from studies on arabidopsis (Arabidopsis thaliana), and it is unclear whether this close relationship is generally conserved across other species. To address this question, we investigated the diel changes in sucrose and Tre6P in leaves from a phylogenetically diverse set of angiosperms with different phloem loading and carbohydrate storage strategies: arabidopsis, Alchemilla molis, strawberry (Fragaria×ananassa), Plantago major, melon (Cucumis melo), and wheat (Triticum aestivum). Despite large differences in their sucrose and Tre6P levels, there were positive correlations between sucrose and Tre6P across all species. Network analysis confirmed a strong association between Tre6P and sucrose in all species, and also revealed a common link with malate, consistent with positive regulation of malate synthesis by Tre6P. In combination with previous observations that Tre6P is synthesized in and around the leaf vasculature, our findings suggest that Tre6P primarily reflects the vascular transport pool of sucrose in leaves. We conclude that the sucrose-Tre6P nexus is widespread among angiosperms, with a conserved role in regulation of sucrose metabolism and transport.