Biology subjects

Andersen, T. G.

Publications and source records attributed to Andersen, T. G..

17 recordsLinked to original sources

bioRxiv2026

Intronised fluorophores improve reporter output and biosensor expression in plants

Genetically encoded biosensors are central to plant cell biology, but low reporter signal can limit their use. Here, we developed modular intronised fluorophores to improve reporter output in transient and stable plant expression systems. Matched nuclear-localised triple mCitrine and mScarlet3 reporters were compared with and without introduced introns in Nicotiana benthamiana and Arabidopsis thaliana. Intronisation increased fluorescence, with the magnitude of enhancement depending on the fluorophore and expression context. Immunoblot analyses supported increased reporter accumulation. In Arabidopsis, intronised reporters driven by the tissue-specific SCARECROW promoter, produced stronger fluorescence signals that remained detectable farther from the root tip than non-intronised versions. Intronised versions of the abscisic acid (ABA) biosensor ABACUS2 retained ABA responsiveness and showed a lower frequency of reduced fluorescence between generations. These modular components provide a practical toolbox for improving fluorescent reporter detection and maintaining usable biosensor expression, supporting their application in plant cell biology and quantitative imaging.

plant biology↗

bioRxiv2026

A tunable receptor separates root barrier formation from nutrient signaling through ligand-perception states

In roots, the endodermis controls nutrient entry by forming a barrier known as the Casparian strip1-3. Yet how barrier-associated processes interface with systemic signaling remains unclear. Here, we show that the receptor kinase SCHENGEN3 links local barrier surveillance to systemic nutrient signaling, with outputs that depend on the effective state of ligand perception. Unlike in Arabidopsis thaliana, SCHENGEN3 activation in Lotus japonicus requires a distinct cellular competence state and cannot be triggered by exogenous ligands alone, revealing evolutionary divergence in pathway deployment. Cross-species complementation uncouples systemic nitrogen signaling from Casparian strip formation, while transcriptomic and phosphoproteomic analyses reveal largely non-overlapping signaling- and barrier-associated programs that differ between agar and agricultural soil conditions. Mechanistically, receptor-ligand comparisons, engineered receptor variants, and co-receptor mutant analyses show that systemic nitrogen signaling is retained in receptor-perception states that are insufficient to support full Casparian strip establishment. Together, these findings reveal how a shared receptor module can separate developmental and physiological outputs by linking receptor perception state to output specificity.

plant biology↗

bioRxiv2026

A membrane-anchored inhibitor of papain-like cysteine proteases promotes Pseudomonas root colonization

Pseudomonas species, spanning both beneficial and pathogenic lifestyles, possess conserved mechanisms to modulate plant immunity. Nevertheless, the mechanisms by which commensal bacteria establish and maintain host colonization remain poorly understood. Here, we report the characterization of a Pseudomonas chagasin-like protease inhibitor (Cpi1), conserved across pseudomonads representing a novel class of membrane-anchored PLCP inhibitor. Unlike previously described secreted protease inhibitors, P. putida Cpi1 is a lipoprotein localized to the bacterial surface and outer membrane vesicles (OMVs), positioning it to selectively inhibit immune-related papain-like cysteine proteases (PLCPs) during host interactions. Functional assays demonstrated inhibition of maize PLCP activity in the nanomolar range, while cpi1 deletion and chagasin motif mutants exhibited significantly impaired early root colonization, particularly in the meristematic and elongation zones. Besides, lack of cpi1 resulted in an altered structure of a maize root-associated synthetic community. We hypothesize that, Cpi1 may protect critical bacterial surface proteins from cleavage by inhibiting plant proteases and thereby modulate the release of MAMPs, dampening host immune responses. Moreover, the release of Cpi1 via OMVs could further extend its function within the root periphery and the apoplast. Together, our results uncover a conserved, membrane-anchored mechanism among pseudomonads for subverting plant immunity and establishing host-microbe interactions.

microbiology↗

bioRxiv2026

Transport-driven spatial patterning of glucosinolates structures root microbiome assembly

Plant roots actively assemble distinct microbial communities, yet how host chemical traits are organized to structure them remains poorly understood. Glucosinolates are hallmark defense metabolites of Brassicaceae, but their axial distribution in roots and ecological relevance belowground remain largely unknown. Here, we combine spatial metabolite profiling and microbiome analysis in Arabidopsis thaliana and the oilseed crop Camelina sativa using mutants lacking the glucosinolate transporters GTR1 and GTR2. We find that both species exhibit a conserved, transporter-dependent enrichment of long-chained aliphatic glucosinolates at the root tip, revealing active axial organization of chemical defenses in roots. Using 16S rRNA amplicon-based sequencing, we show that plant species identity is the primary determinant of bacterial community composition. However, disruption of axial glucosinolate distribution significantly alters spatial patterns of microbiome assembly along the root in a species-dependent manner. In Arabidopsis, this assembly effect is most pronounced in the rhizosphere, whereas in Camelina, root-associated communities were also affected. Together, our findings demonstrate that glucosinolate transport establishes chemical landscapes along the root axis, thereby shaping spatial patterns of microbiome assembly. This identifies spatially structured specialized metabolite allocation as an important mechanism by which plants shape their belowground microbial environment.

plant biology↗

bioRxiv2025

Suppression of nonsense mutations by small, cyclic peptides

Premature termination codons in mRNAs result from nonsense mutations and hinder the translation of full-length, functional proteins. Nonsense mutations cause numerous serious genetic diseases, including cystic fibrosis and Duchenne muscular dystrophy. Several small-molecule drugs have been reported that could potentially ameliorate these diseases by promoting translational readthrough at the premature termination codon. However, utilization of many of these molecules faces problems such as limited efficacy or high cellular toxicity. Using a selection strategy in Saccharomyces cerevisiae coupling suppression of endogenous nonsense mutations to cell survival, we identified ten readthrough-promoting cyclic peptides from a DNA-encoded library. The selected cyclic peptides suppress nonsense mutations in various reporter genes, and the candidates inducing the highest readthrough levels display no observable cytotoxicity in yeast. Mutational analysis of the most promising cyclic peptide demonstrate that most amino acid side chains contribute to the readthrough-stimulating activity. Importantly, this cyclic peptide appears to bind directly to the eukaryotic core translation machinery and promotes readthrough in vitro by interfering with ribosomal decoding. Our results suggest that small, cyclic peptides selected in vivo could represent a novel drug type to treat the many incurable human genetic diseases that are caused by nonsense mutations.

molecular biology↗

bioRxiv2025

Multilevel analysis of response to plant growth promoting and pathogenic bacteria in Arabidopsis roots and the role of CYP71A27 in this response

Understanding how plants distinguish between commensal and pathogenic microorganisms is one of the major challenges in the plant microbe interaction research. We previously identified a gene encoding CYP71A27 connected to camalexin, which is necessary for a plant growth promoting (PGP) activity of a number of bacterial strains. To dissect its function, we compared multilevel responses in roots of wild type Arabidopsis and the cyp71A27 mutant to two bacterial strains, a PGP Pseudomonas fluorescens CH267 and a pathogen Burkholderia glumeae PG1. We show that incubation with these bacteria leads to significant and distinct transcriptional reprogramming. This is accompanied by a proteome remodelling in both shoots and roots and profound changes in accumulation of many metabolites, primarily sugars, amino acids, and TCA cycle intermediates, but also by alterations in the ionome. We then analysed the mutant cyp71a27 and identified number of genes and proteins differently regulated, particularly after interaction with the PGP strain, but only a very mild impact of the mutation on root metabolites and exudates. We analysed a variety of mutants in genes differentially regulated by Pseudomonas sp. CH267 in cyp71a27 and revealed that their response to this PGP bacterial strain is similar to cyp71a27. Thus, it seems that CYP71A27 is a non-canonical P-450 without a metabolic function but active in signalling pointing to a regulatory role of the CYP71A27 gene, particularly in interaction with a plant growth promoting bacteria.

plant biology↗

bioRxiv2024

MYB68 regulates suberin patterning and radially distinct endodermal differentiation

Roots are composed of concentric tissue layers that embrace the centrally localized vasculature. Of these layers, particularly the endodermis stands out as it contains barriers that facilitate selective uptake across the plasma membrane. In mature root regions, endodermal cells undergo additional differentiation and become coated with suberin, a hydrophobic polymer that blocks membrane transport and seals off the inner root parts. Intriguingly, individual cells adjacent to the water-conducting xylem remain unsuberized. These are termed "passage cells", based on the assumption that they facilitate radial vascular access in a zone which is otherwise impenetrable. The identity of passage cells remain unknown, but their existence suggests that distinct identities and developmental trajectories exist within the second differentiation of the endodermis. In this study, we investigate this in the model plant Arabidopsis thaliana. Our work identifies a genetic regulator that controls pole-specific endodermal differentiation and tissue-forming divisions connected to passage cells. Through a number of analyses, we provide spatiotemporal insights into suberization, establish a framework for radial organization of the endodermis and highlight putative function(s) of passage cells. Combined our findings illustrate how multi-dimensional developmental proceses integrate with environmental inputs in order to provide distinct cellular functions within root tissues.

plant biology↗

bioRxiv2024

MYB68 orchestrates cork differentiation by regulating stem cell proliferation and suberin deposition

Plants have developed specialized barriers to protect and isolate the inner tissues from the environment while maintaining homeostasis. Different barriers are present in various organs and at different growth stages. During secondary growth, the periderm acts as the protective tissue, covering roots, stems, and branches as they become thick. The periderm is a dynamic barrier comprising a stem cell niche known as the cork cambium, which bifacially divides to generate the phelloderm inward and the cork outward. Cork cells have a unique cell wall impregnated with suberin and lignin polymers, essential for the barrier function. Despite its importance, the differentiation process that forms new cork cells from the stem cell is largely unknown. In this work, we identify members of the MYB36-subclade transcription factors as key regulators of cork differentiation. On the one hand, this set of transcription factors promotes suberin deposition by inducing the expression of enzymes involved in all steps of suberin biosynthesis, including the recently discovered suberin-polymerizing enzymes GDS Lipases; on the other hand, it represses cork cambium proliferation. Furthermore, we demonstrated that suberin deposition in the cork is a robust process regulated by a complex network of transcription factors, including other MYB transcription factors that activate suberin deposition in the endodermis. However, only members of the MYB36 subclade can repress cell proliferation in different developmental contexts, highlighting general and specific functions for MYB transcription factors. These findings have broad applicability, as tissue-specific manipulation of MYB activity has the potential for improving traits of biotechnological interest, such as thicker periderms and more suberized cork layers, and for assessing how these traits affect plant performance in response to stresses.

plant biology↗

bioRxiv2023

Apoplastic barrier establishment in roots and nodules of Lotus japonicus is essential for root-shoot signaling and N-fixation

The molecular framework underlying apoplastic root barrier formation has been unveiled in the model species Arabidopsis thaliana where establishment of Casparian strips occurs at an early stage of root development. In legumes, this region overlaps with the area where nitrogen-fixing bacteria can induce nodule formation, termed the susceptible zone. Moreover, while nodules themselves also contain an endodermis spanning their vascular bundles, it is current unknown if Casparian strips serve as a filter for transport across this specialized organ. Here we establish barrier mutants in the symbiosis model Lotus japonicus. We find that the while genetic network controlling Casparian strip formation is conserved in this legume species, formation of functional barriers is crucial for establishment of N-fixing nodules. By probing this in detail, we establish a model where the Casparian strip, via its linked Schengen pathway, converge with long distance N signaling and systemic regulation of nodulation. Moreover, this also reveal that the genetic system for barrier establishment in the root endodermis is shared in nodule vascular endodermis and required for nodule function. Combined, our findings uncover a novel role of apoplastic root barriers and establishes a mutant collection suitable to probe the role of root barriers in symbiotic plant-microbe relationships.

plant biology↗

bioRxiv2023

Timing of root barriers controls soil-to-shoot integration of rhizosphere status

In roots, formation of the Casparian strip in the endodermal cell walls provides a mechanism for selective uptake of nutrients and water. Establishment of this filter is under spatial surveillance by a receptor-ligand mechanism termed the Schengen pathway. This system provides a mechanism to initiate downstream signaling responses in case of dysfunctional barrier establishment. Due to this interconnected nature, the endogenous physiological role of this survaillance mechanism remain difficult to untangle from the direct barrier function. This is in particularly evident in complex growth setups where multiple inputs are integrated into general whole-plant responses. In this work, we address this by rewiring the genetic network that underlies root barrier formation. We create plants with enhanced, Schengen-independent Casparian strip formation that are not only suitable to probe the role of stronger barrier establishment, but also to evaluate the associated signaling output independently. With focus on the latter, we subjected the rewired plants, as well as a number of established barrier mutants, to multifaceted growth conditions including nitrogen fertilized agricultural soil conditions. By profiling their above- and belowground (a)biotic responses our work reveals that, while increased Casparian strip formation mainly provides the plant with an improved stress resistance, the Schengen pathway is necessary for establishment of a growth-promoting root microbiome and serves to convey information of soil nitrogen status to the shoot. This identifies the Schengen pathway as an essential receptor-based signaling hub for adaptive integration of barrier status, nutritional responses and (a)biotic signaling between above- and belowground tissues.

plant biology↗

bioRxiv2022

Auxin-dependent acceleration of cell division rates regulates root growth at elevated temperature

Roots are highly plastic organs enabling plants to acclimate to a changing below-ground environment. In addition to abiotic factors like nutrients or mechanical resistance, plant roots also respond to temperature variation. Below the heat stress threshold, Arabidopsis thaliana seedlings react to elevated temperature by promoting primary root growth, possibly to reach deeper soil regions with potentially better water saturation. While above-ground thermomorphogenesis is enabled by thermo-sensitive cell elongation, it was unknown how temperature modulates root growth. We here show that roots are able to sense and respond to elevated temperature independent of shoot-derived signals. A yet unknown root thermosensor seems to employ auxin as a messenger to promote primary root growth. Growth is primarily achieved by accelerating cell division rates in the root apical meristem, likely maintained via temperature-sensitive organization of the polar auxin transport system. Hence, the primary cellular target of elevated ambient temperature differs fundamentally between root and shoot tissues, while the messenger auxin that relays temperature information to elongating or dividing cells, respectively, remains the same.

plant biology↗

bioRxiv2022

Modulation of Arabidopsis growth by volatile organic compounds from a root-derived bacterial community

Plant roots are surrounded by fluctuating biotic and abiotic factors. The living component - the microbiota - is actively shaped by the plant and plays an important role in overall plant health. While it has been shown that specialized metabolites exuded from the plant are involved in shaping host interactions with the microbiota, it is unclear how underground volatile organic compounds (VOCs) influence this communication. This is especially true for root-associated bacteria which are known to release VOCs that can influence plant growth. Using a simplified synthetic bacterial community (SynCom) representing the phylogenetic diversity of bacteria in the root microbiome, we set out to characterize plant growth and defense metabolites when subjected to bacterial VOCs (bVOCs). Moreover, by profiling the SynCom community composition after co-cultivation with the plant, we explored how members of the community influenced each other in our growth setup. Our findings reveal that plant growth promotion can occur via VOCs from a bacterial SynCom, but that the plant response differs for individual community members. In addition, we find that bVOCs are able to repress chemical defense responses in the plant, possibly to facilitate colonization. By removing key species from the SynCom, we find that complex bacteria-bacteria interactions are likely to underlie this phenomenon, and that bVOC-induced modulation of plant responses in the rhizosphere may be an emergent property of bacterial communities rather than depending on individual species.

plant biology↗

bioRxiv2021

Phellem translational landscape throughout secondary development in Arabidopsis roots

O_LIThe phellem is a specialized boundary tissue providing the first line of defense against abiotic and biotic stresses in organs undergoing secondary growth. Phellem cells undergo several differentiation steps, which include cell wall suberization, cell expansion and programmed cell death. Yet, the molecular players acting particularly in phellem cell differentiation remain poorly described, particularly in the widely used model plant Arabidopsis thaliana. C_LIO_LIUsing specific marker lines we followed the onset and progression of phellem differentiation in A. thaliana roots, and further targeted the translatome of new developed phellem cells using Translating Ribosome Affinity Purification followed by mRNA sequencing (TRAP-SEQ). C_LIO_LIWe showed that phellem suberization is initiated early after phellogen (cork cambium) division. The specific translational landscape was organized in three main domains related to energy production, synthesis and transport of cell wall components, and response to stimulus. Novel players in phellem differentiation, related to suberin monomer transport and assembly, as well as novel transcription regulators were identified. C_LIO_LIThis strategy provided an unprecedented resolution of the transcriptome of developing phellem cells, giving a detailed and specific view on the molecular mechanisms controlling cell differentiation in periderm tissues of the model plant Arabidopsis. C_LI Significance statementTo improve the understanding of phellem differentiation into a suberized protective layer, we followed the establishment of periderm in Arabidopsis roots and sequenced the phellem-specific translatome. We found that phellem suberization occurs shortly after pericycle cell divisions with the induction of pivotal suberin biosynthesis genes. In parallel, we detected the activation of three central genetic modules acting throughout the phellem differentiation. This study provides a unique and targeted genetic resource for further functional studies of phellem tissues.

plant biology↗

bioRxiv2021

Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

Suberin is a hydrophobic biopolymer that can be deposited at the periphery of cells, forming protective barriers against biotic and abiotic stress. In roots, suberin forms lamellae at the periphery of endodermal cells where it plays crucial roles in the control of water and mineral transport. Suberin formation is highly regulated by developmental and environmental cues. However, the mechanisms controlling its spatiotemporal regulation are poorly understood. Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine tune suberin deposition in roots. We found a set of four MYB transcription factors (MYB41, MYB53, MYB92 and MYB93), that are regulated by these two signals, and are sufficient to promote endodermal suberin. Mutation of these four transcription factors simultaneously through genome editing, lead to a dramatic reduction of suberin formation in response to both developmental and environmental signals. Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips), through a compensatory mechanism. Through the functional analysis of these four MYBs we generated plants allowing unbiased investigations of endodermal suberin function without accounting for confounding effects due to Casparian strip defects, and could unravel specific roles of suberin in nutrient homeostasis.

plant biology↗

bioRxiv2020

Tissue-autonomous phenylpropanoid production is essential for establishment of root barriers

Plants deposit polymeric barriers in their root cell walls to protect against external stress and facilitate selective nutrient uptake. The compounds that make up these barriers originate from the fatty acid- and phenylpropanoid biosynthetic pathways. Although the machinery responsible for production of the barrier constituents is well-char-acterized, our pathway models lack spatiotemporal resolution - especially in roots - and the source tissue is often not clear due to the apoplastic nature of barriers. Insights into how the individual root tissues or cells contribute to forming apoplastic barriers is important for elucidation of their ultrastructure, function and development. Manipulation of the associated biosynthesis is delicate, as mutants often display pleiotropic phenotypes due to the broad role of the underlying metabolites. Here, we address these issues by creating a genetic tool that allows in vivo repression of the phenylpropanoid pathway with both spatial and temporal control. We provide strong evidence that tissue-auton-omous production of phenylpropanoids is essential for establishment of the endodermal Casparian strip. Moreover, we find that in order to maintain deposition and attachment of a coherent suberin matrix to the cell wall, cells require continuous production of aromatic constituents. This process is especially crucial in the suberized endodermis where we find that repression of phenylpropanoid production leads to active removal of suberin.

plant biology↗

bioRxiv2019

ROS production by localized SCHENGEN receptor module drives lignification at subcellular precision

Production of reactive-oxygen species (ROS) by NADPH oxidases (NOXs) impacts many processes in animals and plants and many plant receptor pathways involve rapid, NOX-dependent increases of ROS. Yet, their general reactivity has made it challenging to pinpoint the precise role and direct cellular targets of ROS. A well-understood ROS target in plants are lignin peroxidases in the cell wall. Lignin can be deposited with exquisite spatial control, but the underlying mechanisms have remained elusive. Here we establish a full kinase signaling relay that exerts direct, spatial control over ROS production and lignification within the cell wall. We show that polar localization of a single kinase component is crucial for pathway function. Our data indicates that an intersection of more broadly localized components allows for micrometer-scale precision of lignification and that this system is triggered through initiation of ROS production as a critical peroxidase co-substrate.

plant biology↗

bioRxiv2017

Minimum requirements for reprogramming and maintaining cell fate in the Arabidopsis root

Changes in gene regulation during differentiation are governed by networks of transcription factors. To identify the minimal network for endodermal differentiation in the Arabidopsis root, we asked what transcription factors are sufficient to program a non-native cell-type into endodermis. Our results show the transcription factors SHORTROOT and MYB36 have limited ability to reprogram a non-native cell-type (the epidermis) and that this reprogramming is reversible in the absence of additional cues. The stele-derived signaling peptide CIF2 stabilizes SHORTROOT-induced reprogramming. The outcome is a partially impermeable barrier deposited in the sub-epidermal cell layer that has a transcriptional signature similar to endodermis. The trans-differentiation mechanism depends on the expression of genes downstream in the gene regulatory network but is independent of SHORTROOT movement. These results highlight a non cell-autonomous induction mechanism for endodermis that resembles differentiation in many animal systems.\n\nOne Sentence SummarySHORTROOT and CIF2 combined can induce and stabilize an endodermis in sub-epidermal cells and do so in a non cell-autonomous manner.

developmental biology↗