Rechercher

Paramétrage

Thèmes

Accessibilité

Accessibilité

Anne-Sophie Blervacq

Maîtresse de conférences-HDR CNU : SECTION 66 - PHYSIOLOGIE

Publications

Article dans une revue scientifique

Compte-rendu et recension critique d'ouvrage

Publications majeures - Major Papers (2022-2025)

Here are Abstracts of the publications in which I am co-author, for 2022-2025:

BLERVACQ A.S., et al. 2025. Tracking ectopic lignification in flax stems following scarification. Plant Physiology and Biochemistry, 223, 109806. https://doi.org/10.1016/j.plaphy.2025.109806 

When flax (Linum usitatissimum L.) stems are scarified, major changes occur in the organization of cell walls within the tissues that border the wound. We sought to characterize the plant's response using a variety of approaches, with a particular focus on lignin deposition within the peripheral fiber cell walls of the stem. Raman spectroscopy and imaging first showed that changes occurred in the polysaccharide matrix of the parenchyma and fiber cell walls. These changes were accompanied by rapid deposition of lignin which initially diffuses centripetally and then, once the vascular cambium was reached, propagates in a periclinal manner until 150 μm from the edges of the wounded zone. Lignin biosynthesis appears to be the result of a de novo activity, as demonstrated by the concomitant accumulation of transcripts corresponding to lignin biosynthesis genes. In addition, using bioorthogonal chemistry approaches, we showed that wounding had enhanced the capacity of fiber cell walls to incorporate modified lignin precursors, in parallel with an increase in transcripts corresponding to peroxidases in the cortical tissues. This incorporation potential was identical for the 3 different types of reporters tested. Our findings demonstrated that mechanical stress can trigger de novo lignification, in a polarized manner within the bast fibers, providing insights into the plasticity of cell wall composition and the potential for modulating fiber properties in flax.

MUKHERJEE S., et al., 2025. Tracking flax dew retting by infrared vibrational spectrosocpy combined with a powerful multivariate statistical analysis. Industrial Crops and Products.  227, 120798. https://doi.org/10.1016/j.indcrop.2025.120798 

Natural fibers are of great interest for the industrial sector, particularly those from flax (Linum usitatissimum L.). Before the industrial process, flax stems have to undergo ‘dew retting’. Under-retting and over-retting can result in fibers with lower industrial value and this process is currently empirical. In this study, we aimed to accurately monitor the flax dew retting by determining FT-IR spectra of uprooted stems after 1-, 6-,  20- and 25 days. As FTIR was usually performed after retting, it is original. With both one-way anova (‘a priori’ approach’) and a multivariate analysis (‘without a priori’ approach), we pinpoint significant markers of the retting progression. But the ‘without a priori’ approach reveals more significant markers. The early retting step was suported by peaks corresponding to esterified and alkyl-esterified pectins (1734 cm-1), other pectin (1335 cm-1) and aromatics (1508 cm-1). Degradation of the epidermis and the middle lamella from cortical parenchyma are taking place early. This is a prerequisite for fungus hyphae or bacteria colonization. The final retting step showed significant contributions from cellulose/hemicellulose peak (1317; 1427 cm-1), crystalline cellulose (1371 cm-1) and, OH- (3270 cm-1). This suggests almost complete outer tissue disorganization as well as the beginning of the release of bast fibers from bundles. Identifying specific peaks related to the end of the retting will help to build a predictive model. This will constitute a valuable tool to parameter a handheld device for helping farmers to determine the optimal retting point to harvest flax stems ensuring maximum fiber quality

MUKHERJEE S., et al. 2024. Metaproteomics identifies key cell wall degrading enzymes and proteins potentially related to inter-field variability in fiber quality during flax dew retting. Industrial Crops and Products, 222, 119907. https://doi.org/10.1016/j.indcrop.2024.119907 

In this study, metaproteomics and biochemical analyses were used to identify for the first time specific proteins and associated micro-organisms responsible for cell wall degrading enzyme activity during dew retting of flax in two adjacent fields in northern France. This approach identified 6032 non-redundant proteins present at 4 key retting stages (R0/day 1, R2/day 6, R4/day 13, and R7/day 25), of which 75 contained CAZy (Carbohydrate Active Enzyme) motifs belonging to 31 different families from all 5 CAZy classes. 19 families were putatively related to the degradation of different plant cell wall polymers including lignin (AA1), pectins (CE13, CE8, PL1, PL3, GH28, GH35), hemicellulose (GH2, GH10, GH26, GH35, GH55, GH3, GH5, GH17) and cellulose (GH5, GH7, GH3, GH94, AA3). Taxonomy of identified proteins indicated that 85 % come from bacteria, 13 % from fungi, and 2 % from plants; however, ~60 % of CAZymes involved in the degradation of plant wall polymers are of fungal origin. Although 88 % of total proteins and almost 65 % of cell wall degrading CAZymes were similar between the two investigated fields, certain differences in the abundance and dynamics of certain CAZymes might be related to observed inter-field variability in cell wall degrading enzyme activities, stem/fiber yield and industrial qualities of fibers harvested from the two fields. Overall, these results highlight the interest of using metaproteomics for improving our biological understanding of how retting impacts fiber quality. In addition, the identification of several new bacterial and fungal species in this study demonstrates that such an approach is also extremely powerful for generating novel taxonomic data. 

CHABI M., et al. 2023. Identification of new potentila molecular actors related to fiber quality in flax through Omics. Frontiers in Plant Science, 14, 1204016. https://doi.org/10.3389/fpls.2023.1204016

One of the biggest challenges for a more widespread utilization of plant fibers is to better understand the different molecular factors underlying the variability in fineness and mechanical properties of both elementary and scutched fibers. Accordingly, we analyzed genome-wide transcription profiling from bast fiber bearing tissues of seven different flax varieties (4 spring, 2 winter fiber varieties and 1 winter linseed) and identified 1041 differentially expressed genes between varieties, of which 97 were related to cell wall metabolism. KEGG analysis highlighted a number of different enriched pathways. Subsequent statistical analysis using Partial Least-Squares Discriminant Analysis showed that 73% of the total variance was explained by the first 3 X-variates corresponding to 56 differentially expressed genes. Calculation of Pearson correlations identified 5 genes showing a strong correlation between expression and morphometric data. Two-dimensional gel proteomic analysis on the two varieties showing the most discriminant and significant differences in morphometrics revealed 1490 protein spots of which 108 showed significant differential abundance. Mass spectrometry analysis successfully identified 46 proteins representing 32 nonredundant proteins. Statistical clusterization based on the expression level of genes corresponding to the 32 proteins showed clear discrimination into three separate clusters, reflecting the variety type (spring-/winter-fiber/oil). Four of the 32 proteins were also highly correlated with morphometric features. Examination of predicted functions for the 9 (5 + 4) identified genes highlighted lipid metabolism and senescence process. Calculation of Pearson correlation coefficients between expression data and retted fiber mechanical measurements (strength and maximum force) identified 3 significantly correlated genes. The genes were predicted to be connected to cell wall dynamics, either directly (Expansin-like protein), or indirectly (NAD(P)-binding Rossmann-fold superfamily protein). Taken together, our results have allowed the identification of molecular actors potentially associated with the determination of both in-planta fiber morphometrics, as well as ex-planta fiber mechanical properties, both of which are key parameters for elementary fiber and scutched fiber quality in flax.

BLERVACQ A.S., et al. 2023. Comparative Analysis of G-Layers in Bast Fiber and Xylem Cell walls in Flax using Raman Spectoscopy. Biomolecules, 13, 435. https://doi.org/10.3390/biom13030435 

In a response to gravitropic stress, G‐layers (gelatinous layers) were deposited in xylem cell walls of tilted flax plants. G‐layers were produced in both tension wood (upper side) as expected but were also observed in opposite wood (lower side). Raman spectral profiles were acquired for xylem G‐layers from the tension and opposite side as well as from the G‐layer of bast fibers grown under non‐tilted conditions. Statistical analysis by principal component analysis (PCA) and partial least square‐discriminant analysis (PLS‐DA) clearly distinguished bast fiber G‐layers from xylem G‐layers. Discriminating bands were observed for cellulose (380–1150–1376 cm–1), hemicelluloses (517–1094–1126–1452 cm–1) and aromatics (1270–1599–1658 cm–1). PCA did not allow separation of G‐layers from tension/opposite‐wood sides. In contrast, the two types of xylem G‐layers could be incompletely discriminated through PLS‐DA. Overall, the results suggested that while the architecture (polymer spatial distribution) of bast fibers G‐layers and xylem G‐layers are similar, they should be considered as belonging to a different cell wall layer category based upon ontogenetical and chemical composition parameters.

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.