Biology subjects

Coll, N. S.

Publications and source records attributed to Coll, N. S..

6 recordsLinked to original sources

bioRxiv2026

The Receptor Kinase MEE39/ATHE Mediates Cell Wall Integrity Surveillance During Root Vascular Pathogen Infection

Plant cell wall (CW) integrity signaling enables early detection of microbial invasion, yet the receptors involved and their spatial and temporal dynamics during infection remain largely unknown. We identify ATHENA (ATHE)/MEE39, a previously uncharacterized malectin-like leucin-rich repeat receptor kinase (Mal-LRR-RK) that contributes to defense against the root vascular pathogen Fusarium oxysporum (Fo), particularly in outer root layers where colonization begins. ATHE abundance, localization, and endocytic trafficking are rapidly remodeled during infection, and loss of ATHE compromises basal immunity and early pathogen-induced transcriptional reprogramming. ATHE responds to altered cellulose synthesis, cellulose-derived oligosaccharides, mechanically induced CW perturbations, and the fungal secreted peptide Fo-RALF. In most of these contexts, ATHE acts together with the LRR-RK MIK2, forming a pathogen-strengthened RK complex that fine-tunes root responses to Fo. This represents the first example of a receptor complex visualized subcellularly in vivo during a plant-microbe interaction. Although Brassicaceae-specific, heterologous expression of ATHE enhanced tomato resistance to Fo, highlighting its functional relevance across plant lineages and its potential use for crop engineering. Our work reveals a previously unrecognized strategy by which plants decode microbial threats through dynamic CW-integrity surveillance.

plant biology↗

bioRxiv2025

Lack of AtMC1 catalytic activity triggers autoimmunity dependent on NLR stability

Plants utilize cell surface-localized pattern recognition receptors (PRRs) and intracellular nucleotide-binding leucine-rich repeat (NLR) receptors to detect non-self and elicit robust immune responses. Fine-tuning the homeostasis of these receptors is critical to prevent their hyperactivation. Here, we show that Arabidopsis plants lacking metacaspase 1 (AtMC1) display autoimmunity dependent on immune signalling components downstream of NLR and PRR activation. Overexpression of a catalytically inactive AtMC1 in an atmc1 background triggers severe autoimmunity partially dependent on the same immune signalling components. Overexpression of the E3 ligase SNIPER1, a master regulator of NLR homeostasis, fully reverts the AtMC1-dependent autoimmunity phenotype, inferring that a broad defect in NLR turnover may underlie the severe phenotype observed. Catalytically inactive AtMC1 localizes to punctate structures that are degraded through autophagy. Altogether and considering previous evidence on the proteostatic functions of AtMC1, we speculate that Wt AtMC1 may either directly or indirectly control NLR protein levels, thereby preventing autoimmunity.

plant biology↗

bioRxiv2024

ATG8ylation of vacuolar membrane protects plants against cell wall damage

Vacuoles are essential for cellular metabolism, growth, and the maintenance of internal turgor pressure. They sequester lytic enzymes, ions, and secondary metabolites that, if leaked into the cytosol, could lead to cell death. Despite their pivotal roles, quality control pathways that safeguard vacuolar integrity remained elusive in plants. Here, we discovered a conserved vacuolar quality control (VQC) pathway that is activated upon cell wall damage in a turgor pressure dependent manner. Cell wall perturbations induce a distinct modification - ATG8ylation - on the vacuolar membrane (tonoplast) that is regulated by the V-ATPase and ATG8 conjugation machinery. Genetic disruption of tonoplast ATG8ylation impairs vacuolar integrity, leading to cell death. Together, our findings reveal a homeostatic pathway that preserves vacuolar integrity upon cell wall damage.

plant biology↗

bioRxiv2022

A phloem-localized Arabidopsis metacaspase (AtMC3) improves drought tolerance

Increasing drought phenomena pose a serious threat to agricultural productivity. Although plants have multiple ways to respond to the complexity of drought stress, the underlying mechanisms of stress sensing and signalling remain unclear. The role of the vasculature, in particular the phloem, in facilitating inter-organ communication is critical. Here, we investigated the role of AtMC3, a phloem-specific member of the metacaspase family, in osmotic stress responses in Arabidopsis thaliana. Overexpression of AtMC3 conferred drought tolerance by enhancing the differentiation of the metaphloem sieve elements and maintaining higher levels of vascular-mediated transportation, whilst plants lacking the protein showed an impaired response to drought and inability to respond effectively to the hormone abscisic acid. Analyses of the proteome in plants with altered AtMC3 levels revealed differential abundance of proteins related to osmotic stress. Overall, our data highlight the importance of AtMC3 and vascular plasticity in fine-tuning early drought responses at the whole plant level without affecting growth or yield.

plant biology↗

bioRxiv2021

Robust transcriptional indicators of plant immune cell death revealed by spatio-temporal transcriptome analyses

Recognition of a pathogen by the plant immune system often triggers a form of regulated cell death traditionally known as the hypersensitive response. This type of immune cell death occurs precisely at the site of pathogen recognition, and it is restricted to a few cells. Extensive research has shed light into how plant immune receptors are mechanistically activated. However, a central key question remains largely unresolved: how does cell death zonation take place and what are the mechanisms that underpin this phenomenon? As a consequence, bona fide transcriptional indicators of immune cell death are lacking, which prevents gaining a deeper insight of its mechanisms before cell death becomes macroscopic and precludes any early or live observation. We addressed this question using the paradigmatic Arabidopsis thaliana-Pseudomonas syringae pathosystem, by performing a spatio-temporally resolved gene expression analysis that compared infected cells that will undergo immune cell death upon pathogen recognition vs by-stander cells that will stay alive and activate immunity. Our data revealed unique and time-dependent differences in the repertoire of differentially expressed genes, expression profiles and biological processes derived from tissue undergoing immune cell death and that of its surroundings. Further, we generated a pipeline based on concatenated pairwise comparisons between time, zone and treatment that enabled us to define 13 robust transcriptional immune cell death markers. Among these genes, the promoter of an uncharacterized AAA-ATPase has been used to obtain a fluorescent reporter transgenic line, which displays a strong spatio-temporally resolved signal specifically in cells that will later undergo pathogen-triggered cell death. In sum, this valuable set of genes can be used to define those cells that are destined to die upon infection with immune cell death-triggering bacteria, opening new avenues for specific and/or high-throughput techniques to study immune cell death processes at a single-cell level.

plant biology↗

bioRxiv2021

Induced ligno-suberin vascular coating and tyramine-derived hydroxycinnamic acid amides restrict Ralstonia solanacearum colonization in resistant tomato roots

The soil borne pathogen Ralstonia solanacearum is the causing agent of bacterial wilt, a devastating disease affecting major agricultural crops. R. solanacearum enters plants through the roots and reaches the vasculature, causing rapid wilting. We recently showed that tomato varieties resistant to bacterial wilt restrict bacterial movement in the plant. In the present work we go a step forward by identifying the physico-chemical nature of the barriers induced in resistant tomato roots in response to R. solanacearum. We describe that resistant tomato specifically responds to infection by assembling de novo a structural barrier at the vasculature formed by a ligno-suberin coating and tyramine-derived hydroxycinnamic acid amides (HCAAs). On the contrary, susceptible tomato does not form these reinforcements in response to the pathogen but instead displays lignin structural changes compatible with its degradation. Further, we show that overexpressing genes of the ligno-suberin pathway in a commercial susceptible variety of tomato restricts R. solanacearum movement inside the plant and slows disease progression, enhancing resistance to the pathogen. We thus propose that the induced barrier in resistant plants does not only restrict the movement of the pathogen, but may also prevent cell wall degradation by the pathogen and confer anti-microbial properties.

plant biology↗