ORCID Profile
0000-0002-9417-1753
Current Organisation
University of Bordeaux
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Publisher: Wiley
Date: 07-08-2023
DOI: 10.1111/NPH.19160
Abstract: The ascorbate–glutathione (ASC–GSH) cycle is at the heart of redox metabolism, linking the major redox buffers with central metabolism through the processing of reactive oxygen species (ROS) and pyridine nucleotide metabolism. Tomato fruit development is underpinned by changes in redox buffer contents and their associated enzyme capacities, but interactions between them remain unclear. Based on quantitative data obtained for the core redox metabolism, we built an enzyme‐based kinetic model to calculate redox metabolite concentrations with their corresponding fluxes and control coefficients. Dynamic and associated regulations of the ASC–GSH cycle throughout the whole fruit development were analysed and pointed to a sequential metabolic control of redox fluxes by ASC synthesis, NAD(P)H and ROS availability depending on the developmental phase. Furthermore, we highlighted that monodehydroascorbate reductase and the availability of reducing power were found to be the main regulators of the redox state of ASC and GSH during fruit growth under optimal conditions. Our kinetic modelling approach indicated that tomato fruit development displayed growth phase‐dependent redox metabolism linked with central metabolism via pyridine nucleotides and H 2 O 2 availability, while providing a new tool to the scientific community to investigate redox metabolism in fruits.
Publisher: Japanese Society for Plant Cell and Molecular Biology
Date: 2013
Publisher: Japanese Society for Plant Cell and Molecular Biology
Date: 2013
Publisher: Oxford University Press (OUP)
Date: 02-02-2021
DOI: 10.1093/JXB/ERAB040
Abstract: Ascorbate is a major antioxidant buffer in plants. Several approaches have been used to increase the ascorbate content of fruits and vegetables. Here, we combined forward genetics with mapping-by-sequencing approaches using an ethyl methanesulfonate (EMS)-mutagenized Micro-Tom population to identify putative regulators underlying a high-ascorbate phenotype in tomato fruits. Among the ascorbate-enriched mutants, the family with the highest fruit ascorbate level (P17C5, up to 5-fold wild-type level) had strongly impaired flower development and produced seedless fruit. Genetic characterization was performed by outcrossing P17C5 with cv. M82. We identified the mutation responsible for the ascorbate-enriched trait in a cis-acting upstream open reading frame (uORF) involved in the downstream regulation of GDP-l-galactose phosphorylase (GGP). Using a specific CRISPR strategy, we generated uORF-GGP1 mutants and confirmed the ascorbate-enriched phenotype. We further investigated the impact of the ascorbate-enriched trait in tomato plants by phenotyping the original P17C5 EMS mutant, the population of outcrossed P17C5 × M82 plants, and the CRISPR-mutated line. These studies revealed that high ascorbate content is linked to impaired floral organ architecture, particularly anther and pollen development, leading to male sterility. RNA-seq analysis suggested that uORF-GGP1 acts as a regulator of ascorbate synthesis that maintains redox homeostasis to allow appropriate plant development.
Publisher: Oxford University Press (OUP)
Date: 13-04-2023
Abstract: Ascorbate (vitamin C) is an essential antioxidant in fresh fruits and vegetables. To gain insight into the regulation of ascorbate metabolism in plants, we studied mutant tomato plants (Solanum lycopersicum) that produce ascorbate-enriched fruits. The causal mutation, identified by a mapping-by-sequencing strategy, corresponded to a knock-out recessive mutation in a class of photoreceptor named PAS/LOV protein (PLP), which acts as a negative regulator of ascorbate biosynthesis. This trait was confirmed by CRISPR/Cas9 gene editing and further found in all plant organs, including fruit that accumulated 2 to 3 times more ascorbate than in the WT. The functional characterization revealed that PLP interacted with the 2 isoforms of GDP-L-galactose phosphorylase (GGP), known as the controlling step of the L-galactose pathway of ascorbate synthesis. The interaction with GGP occurred in the cytoplasm and the nucleus, but was abolished when PLP was truncated. These results were confirmed by a synthetic approach using an animal cell system, which additionally demonstrated that blue light modulated the PLP-GGP interaction. Assays performed in vitro with heterologously expressed GGP and PLP showed that PLP is a noncompetitive inhibitor of GGP that is inactivated after blue light exposure. This discovery provides a greater understanding of the light-dependent regulation of ascorbate metabolism in plants.
Publisher: Oxford University Press (OUP)
Date: 05-07-2016
DOI: 10.1093/JXB/ERW260
No related grants have been discovered for Kentaro Mori.