Biology subjects

El Arbi, N.

Publications and source records attributed to El Arbi, N..

4 recordsLinked to original sources

bioRxiv2025

The Cell Wall Controls Stem Cell Fate in the Arabidopsis Shoot Apical Meristem

At the basis of plant developmental plasticity are continuously active pluripotent stem cells, which fuel the life-long post-embryonic formation of new organs. Since plant cells are encased in cell walls and thus immotile, their individual fate-specification program is dependent on their relative position within the organism. It is assumed that the cell wall and its mechanical properties are under surveillance, linking cell wall state to intracellular gene-regulatory networks. However, the role of these cell wall signalling pathways in plant development and the contribution of cell wall properties to cell behaviour and identity are unclear. Here, we show that control of cell wall properties is essential for the perpetuation of stem cell populations and pattering in the shoot apical meristems. The expression of pectin methylesterases (PMEs), which modify homogalacturonan methylesterification and thereby modulate cell wall mechanics, is maintained at low levels in stem cells by the stem cell specifying transcription factor WUS. Low PME expression is required for stemness, auxin patterning and stem cell-specific mechanical properties. Conversely, WUS depletion reduces wall stiffness in the meristem centre, reinforcing its role in maintaining mechanical homeostasis. Together, our findings show that WUS-mediated control of cell wall-modifying enzymes is essential for sustaining stem cell identity and SAM organization. These results demonstrat that the plant cell wall is not only involved in cell differentiation, but also exerts feedback control on developmental transitions, contributing to our understanding how the immediate physical environment is able to guide cell fate decisions in plants.

plant biology↗

bioRxiv2024

Time and temperature-resolved transcriptomic analysis of Arabidopsis splicing-related mutants

Temperature plays a crucial role in plant growth and development, influencing numerous physiological processes throughout the plant life cycle. Ambient temperature fluctuations can significantly affect transcriptomic adjustments, which are essential for plants to adapt to ever-changing environmental conditions. Despite the known impacts of extreme temperatures on plant physiology, there remains a knowledge gap regarding the specific effects of moderate changes in ambient temperatures on transcriptomic responses. This study employs strand-specific mRNA sequencing (RNA-seq) to assess how different splicing-related mutants respond to varying ambient temperatures, providing a valuable resource to the research community. Analysis of our time-resolved temperature-regulated alternative RNA splicing data reveals that common and exclusive use of the splicing machinery plays pivotal roles in thermoresponsive growth. Furthermore, our analyses demonstrate that moderate temperature changes are translated into widespread transcriptomic responses, including adjustments of the circadian clock and significant splicing changes in light and temperature genes. These results highlight the importance of these particular signaling pathways in adapting to new temperature regimes and suggest future experiments to study the role of alternative RNA splicing in temperature adaptation. Taken together, our results provide insights regarding the role of RNA splicing in plant responses to ambient temperature changes, highlighting the biological relevance of transcriptomic adjustments in enhancing plant resilience and adaptation to climate variability. SIGNIFICANCE STATEMENT- This is the first comprehensive study on how mutants involved in multiple steps of the splicing process modulate splicing activity in response to low and high ambient temperature changes. - We assessed early and acclimated transcriptomic responses and created a valuable resource to investigate the biological outputs.

plant biology↗

bioRxiv2024

The Arabidopsis splicing factor PORCUPINE/SmE1 orchestrates temperature-dependent root development via auxin homeostasis maintenance

O_LIAppropriate abiotic stress response is pivotal for plant survival and makes use of multiple signaling molecules and phytohormones to achieve specific and fast molecular adjustments. A multitude of studies has highlighted the role of alternative splicing in response to abiotic stress, including temperature, emphasizing the role of transcriptional regulation for stress response. Here we investigated the role of the core splicing factor PORCUPINE (PCP) on temperature-dependent root development. C_LIO_LIWe used marker lines and transcriptomic analyses to study the expression profiles of meristematic regulators and mitotic markers, and chemical treatments, as well as root hormone profiling to assess the effect of auxin signaling. C_LIO_LIThe loss of PCP significantly alters RAM architecture in a temperature-dependent manner. Our results indicate that PCP modulates the expression of central meristematic regulators and is required to maintain appropriate levels of auxin in the RAM. C_LIO_LIWe conclude that alternative pre-mRNA splicing is sensitive to moderate temperature fluctuations and contributes to root meristem maintenance, possibly through the regulation of phytohormone homeostasis and meristematic activity. C_LI

plant biology↗

bioRxiv2021

ARGONAUTE10 is required for cell fate specification and the control of formative cell divisions in the Arabidopsis root meristem

A key question in plant biology is how oriented cell divisions are integrated with patterning mechanisms to generate organs with adequate cell type allocation. In the root vasculature, a miRNA gradient controls the abundance of HD-ZIP III transcription factors, which in turn control cell fate and spatially restrict vascular cell proliferation to specific cells. Here, we show that a functional miRNA gradient requires an opposing gradient of ARGONAUTE10, which sequesters miRNAs to protect HD-ZIP III transcripts from degradation. In the absence of ARGONAUTE10, xylem precursor cells undergo periclinal divisions that lead to continuous strands of differentiated xylem elements at ectopic positions. Notably, periclinal daughter cells maintain xylem identity even when they are located outside of the xylem axis, resulting in disrupted tissue boundaries. We further demonstrate that ARGONAUTE10 and HD-ZIP IIIs buffer cytokinin signalling to control formative cell divisions, providing a framework for integration of phytohormone and miRNA-mediated patterning.

plant biology↗