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Anne-Sophie Blervacq

Maîtresse de conférences-HDR CNU : SECTION 66 - PHYSIOLOGIE

Publications

Article dans une revue scientifique

Compte-rendu et recension critique d'ouvrage

Principales publications

BLERVACQ A.S, et al. 2022. Raman spectroscopy mapping of changes in the organization and relative quantities of cell wall polymers in bast fiber cell walls of flax plants exposed to gravitropic stress. Frontiers Plant Science, 13,  doi.org/10.3389/fpls.2022.97635

Flax is an important fiber crop that is subject to lodging. In order to gain more information about the potential role of the bast fiber cell wall in the return to the vertical position, 6-week-old flax plants were subjected to a long-term (6 week) gravitropic stress by stem tilting in an experimental set-up that excluded autotropism. Stress induced significant morphometric changes (lumen surface, lumen diameter, and cell wall thickness and lumen surface/total fiber surface ratio) in pulling- and opposite-side fibers compared to control fibers. Changes in the relative amounts and spatial distribution of cell wall polymers in flax bast fibers were determined by Raman vibrational spectroscopy. Following spectra acquisition, datasets (control, pulling- and opposite sides) were analyzed by principal component analysis, PC score imaging, and Raman chemical cartography of significant chemical bonds. Our results show that gravitropic stress induces discrete but significant changes in the composition and/or spatial organization of cellulose, hemicelluloses and lignin within the cell walls of both pulling side and opposite side fibers.

 

BALDACCI-CRESP F. et al. 2020. A rapid and quantitative safranin-based fluorescent microscopy method to evaluate cell wall lignification. Plant Journal, 102(5), 1074-1089. [FI: 6.417]

Lignin has been studied extensively by a range of different techniques, including anatomical and morphological analyses using dyes to characterize the polymer localization in situ. With the constant improvement of imaging techniques, it is now possible to revisit old qualitative techniques and adapt them to obtain efficient, highly resolutive, quantitative, fast and safe methodologies. In this study, we revisit and exploit the potential of fluorescent microscopy coupled to safranin-O staining to develop a quantitative approach for lignin content determination. The developed approach is based on ratiometric emission measurements and the development of an imagej macro. To demonstrate the potential of our methodology compared with other commonly used lignin reagents, we demonstrated the use of safranin-O staining to evaluate and compare lignin contents in previously characterized Arabidopsis thaliana lignin biosynthesis mutants. In addition, the analysis of lignin content and spatial distribution in the Arabidopsis laccase mutant also provided new biological insights into the effects of laccase gene downregulation in different cell types. Our safranin-O-based methodology, also validated for Linum usitatissimum (flax), Zea mays (maize) and Populus tremula x alba (poplar), significantly improves and speeds up anatomical and developmental investigations of lignin, which we hope will contribute to new discoveries in many areas of cell wall plant research.

 

SIMON C. et al. 2017. BLISS: Shining a light on lignification in plants. Plant Signal. Behavior, 12(8), e1359366. doi: 10.1080/15592324.2017.1359366. [FI : 2.247]

Lignin is a polyphenolic polymer of the plant cell wall formed by the oxidative polymerization of 3 main monomers called monolignols that give rise to the lignin H-, G- and S-units. Together with cellulose and hemicelluloses, lignin is a major component of plant biomass that is widely exploited by humans in numerous industrial processes. Despite recent advances in our understanding of monolignol biosynthesis, our current understanding of the spatio-temporal regulation of their transport and polymerization is more limited. In a recent publication, we have reported the development of an original Bioorthogonal Labeling Imaging Sequential Strategy (BLISS) that allows us to visualize the simultaneous incorporation dynamics of H and G monolignol reporters into lignifying cell walls of the flax stem. Here, we extend the application of this strategy to other plant organs such as roots and rapidly discuss some of the contributions and perspectives of this new technique for improving our understanding of the lignification process in plants

 

LION C. et al. 2017. BLISS: A Bioorthogonal Dual-Labeling Strategy to Unravel Lignification Dynamics in Plants. Cell Chem. Biol., 24, 326–338. [F.I. : 8.116]

This work is among the first carried out as part of our integration into the CNRS in 2015. This publication illustrates the collaborations between two teams from the UMR UGSF, one expert in chemistry-organic chemistry, and the other working on the differentiation cell walls. This involves modifying monolignols, the building block of the lignin polymer (polyphenol). If the determination of lignin (ground material) is feasible, few efficient imaging techniques were available at the histological scale. I helped to optimize and then implement this new technique combining organic chemistry and imaging in confocal microscopy. The modified monolignols were supplied to the plant which integrated them well into the lignin of the wood. This results in a spatio-differential integration in the lignin, and this according to the cell types (vessels, fiber, radius) and according to the types of walls (anticline, pericline).

 

LE ROY J. et al. 2017. Spatial regulation of monolignol biosynthesis and laccase genes control developmental and stress-related lignin in flax. BMC Plant Biol.,  17, 124. [F.I. : 4.215]

This work is among the first carried out as part of our integration into the CNRS in 2015. This publication focuses on the expression of the various genes leading to the production of the 3 monolignols precursors of lignin. This expression regulation differs between flax fibers (hypolignified) and wood. The genes involved in the phenylpropanoid pathway have been identified (in silico approach). The transcripts of 10 of them were localized in the roots, stems and leaves of flax by in situ hybridization. This synthetic pathway is also modified by miRNAs (mir397) which act on the laccases (polymerization phase). Its transcripts have also been localized in flax organs. My contribution was to carry out the in vitro transcription of sense or antisense transcripts from DNA templates, then to perform in situ hybridizations on organ cross-sections.

 

LUCAU-DANILA A. et al. 2012. Transcriptome analysis in pea allows to distinguish chilling and acclimation mechanisms.  Plant Physiol Biochem. 58, 236-44.  [F.I. : 5.4]

This work is the last carried out in collaboration with INRA. In addition to embryogenesis, I have also contributed to the study of the impact of non-freezing cold stress on field crops, in particular to describe the acclimatization of these plants. Two pea varieties, contrasted by their reaction to cold (frost or acclimatization), were compared from the point of view of their transcriptome and on the basis of the histological and morphometric effects observed by these treatments (plasmolysis, root growth vs aerial part). Effects on the cell walls are observed during acclimatization, such as a particular remodeling of pectin, a modification of its dynamics and its expansion. My contribution to this work was to supervise the histological phenotyping (histochemistry in classical light microscopy).