Biology subjects

Vilaine, F.

Publications and source records attributed to Vilaine, F..

5 recordsLinked to original sources

bioRxiv2026

Translational profiling uncovers a tonoplast sugar transporter essential for vascular system development and cell wall composition

The inflorescence stem of Arabidopsis thaliana is a powerful model to study vascular development and carbon allocation, yet the translational landscape underlying xylem differentiation remains poorly defined. Here, we address this gap using tissue-specific Translating Ribosome Affinity Purification sequencing (TRAP-seq) to resolve the translatomes of xylem vessels, xylem parenchyma, and interfascicular fibers. We show that the very early stage of metaxylem differentiation involves coordinated activation of primary metabolism, plastid functions, and cell wall biosynthesis, supporting the metabolic demands of secondary wall formation. Xylem parenchyma displays enrichment in hormone signaling, stress, and immune pathways, consistent with a role in integrating environmental and metabolic cues. Interfascicular fibers exhibit increased translation of ribosomal proteins and spliceosome components, pointing to high translational activity and a role for alternative splicing during late development and programmed cell death. We further identify the tonoplast sugar transporter SUGAR WILL EVENTUALLY BE EXPORTED TRANSPORTER 2 (SWEET2) as a key regulator of stem radial growth. Preferentially translated in early stage of metaxylem differentiation, SWEET2 acts as a rate-limiting component of vacuolar sugar exchange, controlling cytosolic hexose availability for secondary wall biosynthesis. By contrast, SWEET16 and SWEET17 exert more specialized, tissue-specific functions. Together, our findings establish subcellular sugar partitioning as a central determinant of vascular development and highlight the power of translatome profiling.

plant biology↗

bioRxiv2024

SUC2 sucrose transporter is required for leaf apoplasmic sucrose levels. Consequences for phloem loading strategies

Summary * The SUC/SUT sucrose transporters belong to a family of active H+/sucrose symporters, with a role of SUC2 in active apoplasmic phloem loading to drive long-distance phloem transport of sucrose in Arabidopsis. However, the cooperation with the symplasmic pathway for phloem loading remains unclear. * In this study, we explored the consequences of reducing either apoplasmic or symplasmic pathways of phloem loading. We compared a series of lines with modified expression of SUC2 gene, and we analyzed the effects on plant growth, sugar accumulation in source and sink organs, phloem transport, and gene expression. * Our data revealed that a modified expression of SUC2 impacted apoplasmic sucrose levels in source leaves but did not impact phloem transport, as might be expected, while increasing foliar storage of carbohydrates. This response differed from lines in which symplasmic communications between phloem cells was disrupted by the over-expression of a plasmodesmata-associated protein, NHL26. * Altogether, our studies indicate an unexpected effect of SUC2 for apoplasmic sucrose levels in source leaves, together with SUC1, and suggest a feedback regulation on foliar storage. This data sheds new light on the interplay between symplasmic and apoplasmic pathways for sugar loading and the consequences on leaf water flows. Summary statementThe mechanisms that coordinate apoplasmic and symplasmic loading pathways, and their effects on foliar carbon storage, remain largely unexplored. Surprisingly, the sucrose transporter SUC2 plays a significant role in maintaining sucrose levels in the apoplasm, shedding light on how apoplasmic sugar levels and water flows can interact for phloem loading.

plant biology↗

bioRxiv2020

Hexose fluxes, mediated by vacuolar SWEET transporters, are important for xylem development in the inflorescence stem of Arabidopsis thaliana.

In higher plants, the development of the vascular system is controlled by a complex network of transcription factors. However, how nutrient availability in the vascular cells affects their development remains to be addressed. At the cellular level, cytosolic sugar availability is regulated mainly by sugar exchanges at the tonoplast through active and/or facilitated transport. In Arabidopsis thaliana, among the tonoplastic transporters, SWEET16 and SWEET17 genes have been previously localized in the vascular system. Here, using a reverse genetic approach, we propose that sugar exchanges at the tonoplast, regulated by SWEET16, are important for xylem cell division as revealed in particular by the decreased number of xylem cells in the swt16 mutant and the expression of SWEET16 at the procambium-xylem boundary. In addition, we demonstrate that transport of hexoses mediated by SWEET16 and/or SWEET17 is required to sustain the formation of the xylem secondary cell wall. This result is in line with a defect in the xylem cell wall composition as measured by FTIR in the swt16swt17 double mutant and by upregulation of several genes involved in secondary cell wall synthesis. Our work therefore supports a model in which xylem development is partially dependent on the exchange of hexoses at the tonoplast of xylem-forming cells.

plant biology↗

bioRxiv2020

Role of the SUT1 and SUT2 sugar transporters during stolbur phytoplasma infection in tomato

Phytoplasmas inhabit phloem sieve elements and cause abnormal growth and altered sugar partitioning. But how they interact with phloem functions is not clearly known. The phloem responses were investigated in tomato infected by Candidatus Phytoplasma solani, at the beginning of the symptomatic stage of infection, both in symptomatic and asymptomatic leaves, the first symptoms appearing in the sink top leaf at the stem apex. Antisense lines impaired in the phloem sucrose transporters SUT1 and SUT2 were included. The infection in source leaves was not associated with symptoms. In the symptomatic, sink leaf, yellowing and leaf curling was associated with higher starch accumulation and expression of defense genes. The transcriptional analysis of symptomatic leaf midribs indicated that transcript levels for genes acting in the glycolysis and peroxisome metabolism in infected plants differed from these in non-infected plants. Phytoplasma multiplied actively in at least three additional lower leaves although they were symptomless, with no sign of activation of defense markers, although the rate of exudation of sucrose from these symptomless, source leaves was lower for infected plants. A few metabolites in phloem-enriched exudate were affected by the infection, such as glycolate and aspartate, and some of them were also affected in the control SUT1- and SUT2- antisense lines, in which sucrose retrieval or release in the sieve elements are impaired. A metabolic switch could explain the delivery of more glycolate into the sieve elements of infected plants. The findings suggest a link between sugar transport and redox homeostasis. One sentence summaryAn impairment of sucrose retrieval and release in the sieve elements occurs during phytoplasma infection, associated with changes in sugar and peroxisome metabolism

plant biology↗

bioRxiv2018

Synchrotron FTIR and Raman spectroscopy provide unique spectral fingerprints for Arabidopsis floral stem vascular tissues

Cell walls are highly complex structures that are modified during plant growth and development. For example, the development of phloem and xylem vascular cells, which participate in the transport of sugars and water as well as support, can be influenced by cell-specific cell wall composition. Here, we used synchrotron radiation-based infrared (SR-FTIR) and Raman spectroscopy to analyze the cell wall composition of wild-type and double mutant sweet11-1sweet12-1, which impairs sugar transport, Arabidopsis floral stem vascular tissue. The SR-FTIR spectra showed that in addition to modified xylem cell wall composition, phloem cell walls in the double mutant line were characterized by modified hemicellulose composition. Moreover, combining Raman spectroscopy with a Classification and Regression Tree (CART) method identified combinations of Raman shifts that could distinguish xylem vessels and fibers. Additionally, the disruption of SWEET11 and SWEET12 genes impacts xylem cell wall composition in a cell-specific manner, with changes in hemicelluloses and cellulose observed at the xylem vessel interface. These results suggest that the facilitated transport of sugars by transporters that exist between vascular parenchyma cells and conducting cells is important to ensuring correct phloem and xylem cell wall composition.\n\nHighlightCombining vibrational spectroscopy techniques and multivariate analysis shows that the disruption of SWEET genes impacts phloem cell wall composition and that the effect on xylem cell wall composition is cell-specific.

plant biology↗