Biology subjects

Moneger, F.

Publications and source records attributed to Moneger, F..

4 recordsLinked to original sources

bioRxiv2024

Highly expressed cell wall genes contribute to robustness of sepal size

Reproducibility in organ size and shape is a fascinating trait of living organisms. The mechanisms underlying such robustness remain, however, to be elucidated. Taking the sepal of Arabidopsis as a model, we investigated whether variability of gene expression plays a role in variation of organ size and shape. Previous work from our team identified cell-wall related genes as being enriched among the genes whose expression is highly variable. We then hypothesized that the variation of measured morphological parameters in cell-wall related single knockout mutants could be correlated with the variation in gene expression of the corresponding gene (the knocked-out gene) in wild-type plants. We analyzed sepal size and shape from 16 cell-wall mutants and found that sepal size variability correlates positively, not with gene expression variation, but with mean gene expression of the corresponding gene in wild type. These findings support a contribution of cell-wall related genes to the robustness of sepal size.

plant biology↗

bioRxiv2022

Spatial consistency of cell growth direction during organ morphogenesis requires CELLULOSE-SYNTHASE INTERACTIVE1

Extracellular matrices generally contain fibril-like polymers that may be organized in parallel arrays. Although their role in morphogenesis has been long recognized, it is still unclear how the subcellular control of fibril synthesis translates into well-defined organ shape. Here, we addressed this question using the Arabidopsis sepal as a model organ. In plants, cell growth is driven by turgor pressure and restrained by the extracellular matrix known as the cell wall. Cellulose is the main load-bearing component of the plant cell wall and cellulose microfibrils are thought to channel growth perpendicularly to their main orientation. Given the key function of CELLULOSE SYNTHASE INTERACTIVE 1 (CSI1) in guidance of cellulose synthesis, we investigated the role of CSI1 in sepal morphogenesis. We observed that sepals from csi1 mutants are shorter, although their newest cellulose microfibrils are more aligned compared to wild type. Surprisingly, cell growth anisotropy was similar in csi1 and wild-type plants. We resolved this apparent paradox using polarized Raman microspectroscopy, live imaging of growing sepals, and bespoke mechanical assays. We found that CSI1 is required for spatial consistency of growth direction across the sepal and for the maintenance of overall organ elongation. Our work illustrates how the subcellular regulation of the extracellular matrix may control morphogenesis at multiple scales.

developmental biology↗

bioRxiv2022

Robustness of organ morphology is associated with modules of co-expressed genes related to plant cell wall

Control of organ morphology is a fundamental feature of living organisms. There is, however, observable variation in organ size and shape within a given genotype. Taking the sepal of Arabidopsis as a model, we investigated whether we can use variability of gene expression alongside variability of organ morphology to identify gene regulatory networks potentially involved in organ size and shape determination. We produced a dataset composed of morphological parameters and genome-wide transcriptome obtained from 27 individual sepals from wild-type plants with nearly identical genetic backgrounds, environment, and developmental stage. Sepals exhibited appreciable variability in both morphology and transcriptome, with response to stimulus genes and cell-wall related genes displaying high variability in expression. We additionally identified five modules of co-expressed genes which correlated significantly with morphology, revealing biologically relevant gene regulatory networks. Interestingly, cell-wall related genes were overrepresented in two of the top three modules. Overall, our work highlights the benefit of using coupled variation in gene expression and phenotype in wild-type plants to shed light on the mechanisms underlying organ size and shape determination. Although causality between gene expression and sepal morphology has not been established, our approach opens the way to informed analysis for mutant characterization and functional studies.

plant biology↗

bioRxiv2019

Xyloglucan homeostasis and microtubule dynamics synergistically maintain meristem geometry and robustness of phyllotaxis in Arabidopsis

The shoot apical meristem (SAM) gives rise to all aerial organs of the plant. The cell walls are supposed to play a central role in this process, translating molecular regulation into dynamic changes of growth rates and directions, although their precise role in morphogenesis during organ formation remains not well understood. Here we investigate the role of xyloglucans (XyGs), which form a major, yet functionally poorly characterized, wall component in the SAM. Using immunolabeling, biochemical analysis, genetic approaches, micro-indentation, laser ablations and live imaging, we show that XyGs are important for meristem shape and phyllotaxis, although no difference in cell wall stiffness could be observed when XyGs are perturbed. Mutations in enzymes required for XyG synthesis also affect other cell wall components such as cellulose content and the pectin methylation status. Interestingly, we show that the control of cortical microtubules dynamics by the severing enzyme KATANIN becomes vital when XyGs are perturbed or absent. This suggests an active role of the cytoskeleton in compensating for altered wall composition.

plant biology↗