A plastid carbohydrate carrier mediates ribose recycling from nucleotide catabolism and glucose export from starch degradation

authored by

Luisa Voß, Isabel Keller, Rebekka Schröder, Denise Mehner-Breitfeld, André Specht, Gerald Dräger, Jannis Rinne, Jakob Franke, Maria de las Nieves Medina Escobar, Marco Herde, Thomas Brüser, H. Ekkehard Neuhaus, C.-P. Witte

Abstract

In plants, nucleotide degradation releases ribose in the cytosol. An unidentified transporter then brings the ribose into the plastids for phosphorylation. This process of ribose recycling is particularly prominent in root nodules of soybean (Glycine max) and common bean (Phaseolus vulgaris) during symbiotic nitrogen fixation. In this biological context, we identified a plastid ribose transporter, which is an ortholog of the putative plastid glucose transporter (pGlcT) of Arabidopsis thaliana. We show that Arabidopsis mutants of At-pGlcT, but not of the related At-pGlcT2, accumulate ribose and fructose constitutively, whereas glucose accumulates only at night. Uridine feeding experiments leading to cytosolic ribose release indicated that At-pGlcT transports ribose from the cytosol into the plastids. Uptake assays with complemented Escherichia coli sugar transport mutants directly demonstrated that At-pGlcT transports ribose, glucose, and fructose. Ribose and fructose accumulation were also observed in CRISPR-induced bean nodule mutants of Pv-pGlcT. Additionally, our data show that ribose recycling is important for producing allantoin, a nitrogen fixation product used for nitrogen export from nodules to shoots. We conclude that pGlcT is a plastid facilitator for the import of ribose from nucleotide catabolism, for the export of glucose from nocturnal starch breakdown, and for cytosol-plastid fructose exchange in vivo.

Organisation(s)

Institute of Plant Nutrition
Institute of Microbiology
Institute of Organic Chemistry
Section Synthetic Chemistry
Department for Mass Spectrometry
Institute of Botany

External Organisation(s)

University of Kaiserslautern

Type

Article

Journal

Nature Communications

Volume

16

ISSN

2041-1723

Publication date

05.11.2025

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

General Chemistry, General Biochemistry,Genetics and Molecular Biology, General, General Physics and Astronomy

Electronic version(s)

https://doi.org/10.1038/s41467-025-65510-8 (Access: Open)