Biology subjects

Neumann, U.

Publications and source records attributed to Neumann, U..

At least 19 recordsLinked to original sources

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

Tumors accumulate expanded GATA3-dependent tissue Tregs

Targeting Tregs is a potential strategy to improve cancer therapies. However, which Tregs accumulate in response to tumoral processes, and how tumors affect their phenotype, is poorly understood. Here we show that tumor Tregs are equivalent to effector tissue Tregs in steady state organs. We used a mouse model of intestinal neoplasia to demonstrate that one early event in carcinogenesis is sufficient to induce local accumulation of Tregs resembling human tumor Tregs. Treg accumulation was driven by TCR-dependent oligoclonal expansion of tissue Tregs with an effector Treg phenotype. Treg expansion was independent of CCR8, IL33R and CD137, which were previously linked to tumor Treg. In contrast, GATA3 was required for effector tissue Tregs and for their expansion in response to neoplasia. Our findings identify GATA3-dependent clonal expansion of effector tissue Tregs as a key event in promoting tumor growth. HighlightsO_LIAn early tumorigenic event alone drives accumulation of effector tissue Tregs C_LIO_LITregs in tumors are phenotypically akin to effector tissue Tregs C_LIO_LIThe accumulation of Tregs is driven by TCR-dependent oligoclonal expansion C_LIO_LIGATA3 controls tumor-promoting effector tissue Tregs C_LI

immunology↗

bioRxiv2026

CESA7 and microtubules pattern complex secondary cell walls in explosive fruit

Secondary cell walls (SCW) constitute the most abundant form of renewable plant biomass and are major sinks for atmospheric carbon. Their highly ordered patterns underpin specialized cell functions. In Cardamine hirsuta, the geometry of a polarly localized SCW in fruit endocarp b (endb) cells determines the mechanics of explosive seed dispersal. Yet, the genetic control of SCW synthesis and patterning in these specialized cells remains poorly understood. Here we show that CELLULOSE SYNTHASE 7 (CESA7) is required to synthesize SCW cellulose in endb cells. While lignin and xylan deposition occurs independently of cellulose patterning in cesa7 endb SCWs, the final geometry and layered organization of wild-type endb SCWs depend on CESA7. Cellulose serves as a scaffold for the organized assembly of SCW polymers, thereby maintaining the precise SCW patterns observed in endb cells of fruits and metaxylem cells in roots. Cortical microtubules guide the patterned deposition of cellulose, lignin and xylan in endb cells, creating SCW-depleted domains along cell edges that produce the specific hinged SCW geometry. Disrupting microtubules abolished this pattern and prevented explosive coiling of the fruit valves. Our findings show that microtubules and CESA7 shape the form and function of endb SCWs in exploding seed pods.

plant biology↗

bioRxiv2026

Sex without crossovers mimics clonal reproduction in the holocentric plant Rhynchospora tenuis

Meiotic recombination ensures accurate chromosome segregation and promotes genetic diversity by generating crossovers between homologous chromosomes1. While essential in most sexually reproducing organisms, recombination is variably regulated and can be absent in some lineages, a condition known as achiasmy2. However, obligate achiasmy in both sexes of a sexual species has not been previously documented. Here, we investigate the beak-sedge Rhynchospora tenuis, a holocentric plant with the lowest known chromosome number among flowering plants (n = 2) and inverted meiosis3. Using chromosome-scale genome assemblies from nine accessions, molecular cytogenetics, immunocytochemistry, high-throughput single-gamete sequencing and whole-genome sequencing of controlled crosses, we show that R. tenuis undergoes obligate, genome-wide achiasmy in both male and female meiosis. Despite normal early meiotic axis formation, synapsis fails, crossovers are not detected cytologically or genetically, and univalents persist at metaphase I. Extensive haplotype-specific accumulation of transposable elements (TEs) generates segregation distortion (e.g. meiotic drive), favouring the transmission of larger, TE-rich chromosomes. Remarkably, sexual reproduction is retained with fertilisation producing viable seeds only when translocation-compatible gametes meet, indicating strong post-meiotic selection that eliminates incompatible homozygous combinations. As a result, all surviving offspring are genetically identical to the maternal genotype, effectively restoring heterozygosity each generation and mimicking clonal reproduction. We propose that the combined effects of recombination loss, low chromosome number, holocentricity, inverted meiosis, and selective transmission of longer chromosomes enable faithful segregation and clonal-like inheritance despite sexual reproduction. These findings challenge the boundary between sex and clonality, revealing a unique evolutionary strategy linking genome architecture, recombination loss, and transmission bias.

evolutionary biology↗

bioRxiv2024

A versatile protocol for purifying recombinant proteins from Nicotiana benthamiana for structural studies

Structural biology is an essential tool for understanding the molecular basis of biological processes. Although predicting protein structures by fold recognition algorithms has become increasingly powerful, especially with the integration of deep-learning approaches, experimentally resolved structures are indispensable for guiding structure-function studies and for improving modelling. However, experimental structural studies of protein complexes are still challenging, owing to, for example, the necessity for high protein concentrations and purity for downstream analyses such as cryogenic electron microscopy (cryo-EM). The use of Nicotiana benthamiana leaves as a transient expression system for recombinant proteins has become an increasingly attractive approach as the plant is inexpensive to cultivate, grows rapidly, allows fast experimental turnaround and is easily scalable compared to other established systems such as insect cell cultures. Using N. benthamiana as an expression system, we present here a robust and versatile protocol for the purification of five heterocomplexes with sizes ranging from [~]140 kDa to [~]660 kDa consisting of immunoreceptors and their associated pathogen effectors, followed by electron microscopy. The plant-based protocol was applied to verify the structure of the insect cell-derived wheat Sr35 resistosome and to co-purify and co-resolve a [~]140 kDa homodimer of the AvrSr35 effector from the fungus Puccinia graminis f sp tritici (Pgt). In several cases, only a single epitope tag is needed for complex purification, reducing complications that come with multiple epitope tags and two-step affinity purifications. We identify codon usage, signal peptide fusion, epitope tag choice and detergents as critical factors for expression and purification of recombinant protein from N. benthamiana leaves.

biochemistry↗

bioRxiv2024

The barley MLA13-AVRA13 heterodimer reveals principles for immunoreceptor recognition of RNase-like powdery mildew effectors

Co-evolution between cereals and pathogenic grass powdery mildew fungi is exemplified by sequence diversification of an allelic series of barley resistance genes encoding Mildew Locus A (MLA) nucleotide-binding leucine-rich repeat (NLR) immunoreceptors with a N-terminal coiled-coil domain (CNLs). Each immunoreceptor recognises a matching, strain-specific powdery mildew effector encoded by an avirulence gene (AVRa). We present here the cryo-EM structure of barley MLA13 in complex with its cognate effector AVRA13-1. The effector adopts an RNase-like fold when bound to MLA13 in planta, similar to crystal structures of other RNase-like AVRA effectors purified from E. coli. AVRA13-1 interacts via its basal loops with MLA13 C-terminal leucine rich repeats (LRRs) and the central winged helix domain (WHD). Co-expression of structure-guided MLA13 and AVRA13-1 substitution variants show that the receptor-effector interface plays an essential role in mediating immunity-associated plant cell death. Furthermore, by combining structural information from the MLA13-AVRA13-1 heterocomplex with sequence alignments of other MLA receptors, we designed a single amino acid substitution in MLA7 that enables expanded effector detection of AVRA13-1 and the virulent variant AVRA13-V2. In contrast to the pentameric conformation of previously reported effector-activated CNL resistosomes, MLA13 was purified and resolved as a stable heterodimer from an in planta expression system. Our study suggests that the MLA13-AVRA13-1 heterodimer might represent a CNL output distinct from CNL resistosomes and highlights opportunities for the development of designer gain-of-function NLRs.

plant biology↗

bioRxiv2024

Shift in cellular crosstalk reveals the immunosuppressive environment in cholangiocarcinoma patients.

Background and aimsCholangiocarcinoma (CCA) is a deadly disease, and this cancer entity is characterized by an abundant stroma. The tumor microenvironment (TME) plays an important role in aggressive behavior and poor response to therapeutics; however, underlying pathways are unknown. MethodsTo fill this gap, we used multiplexed immunohistochemistry, high-dimensional phenotyping, and transcriptomics to analyze human CCA samples and identify cell cluster crosstalk in patients with a poor prognosis. ResultsOur findings confirmed the presence of Tregs and the lack of effector memory cells in the tumor. New findings are the spatiality of the effector memory cells being more present in the peripheral tissue, for some reason these immune cells fail to reach the tumor niche. We revealed cancer crosstalk with macrophages and stromal cells and identified responsible genes in the poor prognosis group. Amongst the responsible ligand pairs are GAS6-AXL belonging to the TAM family. We then identified VCAN-TLR2 to be present and influencing the ECM in a way to supports immune exhaustion. Last, EGFR-TGF-{beta} is expressed in macrophages and this finding is important in Tregs induction and blocking cytotoxic T cell function. ConclusionsThe multiple mechanisms leading to the exclusion of relevant immune cells needed for an anti-cancer response and mechanisms leading to active immune suppression are part of complex cell-cell crosstalk. This study provides a deeper insight into the immune exhausted phenotype in CCA.

cancer biology↗

bioRxiv2024

Amphicarpic development in the emerging model organism Cardamine chenopodiifolia

O_LIAmphicarpy is an unusual trait where two fruit types develop: one above and the other below ground. This trait is not found in conventional model species, therefore, its development and molecular genetics remain under-studied. Here, we establish Cardamine chenopodiifolia as an emerging experimental system to study amphicarpy. C_LIO_LIWe characterized the development of C. chenopodiifolia, focusing on differences in morphology and cell wall histochemistry between above- and below-ground fruit. We generated a reference transcriptome using PacBio full-length transcript sequencing (IsoSeq) and used a combination of short and long read sequencing to analyse differential gene expression between above- and below-ground fruit valves. C_LIO_LIC. chenopodiifolia has two contrasting modes of seed dispersal. The main shoot fails to bolt and initiates floral primordia that bury underground where they self-pollinate and set seed. By contrast, axillary shoots bolt to position flowers and exploding seed pods above ground. Morphological differences between aerial explosive fruit and subterranean non-explosive fruit were reflected in a large number of differentially regulated genes involved in photosynthesis, secondary cell wall formation and defence responses. C_LIO_LITools established in C. chenopodiifolia, such as a reference transcriptome, draft genome assembly and stable plant transformation, pave the way to explore under-studied traits and discover new biological mechanisms. C_LI

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

TIGIT drives the immunosuppressive environment by downregulation of metalloproteinases MMP2 and MMP14 in perihilar cholangiocarcinoma.

BackgroundCheckpoint blockade in cholangiocarcinoma (CCA) is promising; however, little is known about the response to treatment in CCA subtypes. In this study, we investigated the spatial immune environment in combination with checkpoint expression in perihilar CCA (pCCA). Materials & MethodsThe levels of checkpoint molecules (PD-1, PD-L1, PD-L2, LAG-3, ICOS, TIGIT, TIM-3, and CTLA-4), macrophages (CD68), and T cells (CD4 and CD8) were assessed by multiplex immunofluorescence (mIF) in 50 patients. We investigated the transcriptomic profile using the NanoString Cancer Progression Panel, and validation was performed by mIF on tissue sections from 24 patients. ResultsThe expression of checkpoint molecules TIGIT, CTLA-4, and LAG-3 alone and in combination with other checkpoint molecules was more abundant in the Central Tumor (CT) and Invasive Margin (IM) than in peritumoral tissue (PT) (CD4 and CD8 TIGIT p<0.0001 for both CD4 and CD8 CTLA-4, p<0.0001 and p < 0.001, respectively, and CD8 LAG-3 p < 0.05). MMP2 and MMP14 were differentially expressed in patients with high TIGIT expression. ConclusionThe immune environment in pCCA is characterized by the expression of multiple checkpoints, demonstrating the complexity of ICI treatment. High TIGIT expression drives an immunosuppressive environment by modulating the extracellular matrix. Future clinical trials in pCCA could consider TIGIT as a therapeutically relevant target for (combination) treatment.

cancer 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↗

bioRxiv2023

An optimized workflow for analyzing extracellular vesicles as biomarkers in liver diseases.

Background & AimsExtracellular vesicles (EVs) play an important role in intercellular communication, serving as vehicles for the exchange of biological materials and being involved in the regulation of physiological processes. EVs and their associated cargoes are considered a promising source of disease-associated biomarkers. The purpose of this study was to establish an easy-to-use, reproducible, and scalable workflow to efficiently analyze EVs in the context of liver disease. MethodsAn optimized workflow was established for the pre-analytical processing and isolation of EVs from plasma and serum. Nanoparticle Tracking Analysis (NTA) was used to characterize circulating EVs in the serum of patients with nonalcoholic fatty liver disease (NAFLD), autoimmune liver disease (AIH), and animal models with impaired liver function. EVs were separated from soluble proteins by an optimized, polyethylene glycol (PEG)-based enrichment protocol. Enriched EVs were either labeled and functionally characterized by monitoring cellular uptake or lysed for biomarker identification. ResultsCirculating EVs in the serum of patients with NAFLD or AIH and in different animal models have been characterized by NTA. Here we show that both the quantity and size of EVs in the serum of patients/animal models are significantly different from those of healthy individuals. We show that isolated EVs are functional, and their uptake by acceptor cells can be quantified after fluorescence labelling. Enriched EVs were directly used to analyze RNA biomarkers. Several microRNAs, including miR-15b, -16, -21, -122 and -223, were found to be significantly up-regulated in EVs isolated from the sera of patients with NAFLD and AIH. We show that EVs transport cytokines, and that IL-2, IL-6 and IL-8 were significantly up-regulated in EVs enriched from patients with cholangiocarcinoma (CCA) compared to healthy controls. ConclusionsThe workflow presented here represents an accessible and easy-to-use approach that enables the analysis and enrichment of EVs from complex biological fluids and their preparation for functional characterization or downstream analysis. In this study, the levels of several miRNAs were found to be significantly increased in EVs isolated from AIH and NAFLD patients compared with healthy controls. HighlightsO_LIEVs circulating in crude serum reflect the diseased stage of the donors. C_LIO_LIEnrichment of EVs with the approach presented here efficiently separates soluble proteins from EVs, providing optimal material for further characterization. C_LIO_LIExosomal markers are present in the EVs-enriched fraction. C_LIO_LIEnriched EVs are intact and are functionally taken up by acceptor cells. C_LIO_LIEnriched EVs are suitable, and have been used for, biomarkers identification both at RNA and protein level. C_LI

molecular biology↗

bioRxiv2022

A high confidence Physcomitrium patens plasmodesmata proteome by iterative scoring and validation reveals diversification of cell wall proteins during evolution

Cells of multicellular organisms exchange nutrients, building blocks and information. In animals, this happens via gap junctions, in plants via plasmodesmata (PD). PD have striking properties, translocating a large range of molecules from ions, to metabolites, RNA and proteins up to 40 kDa. PD are hard to characterize due to being deeply embedded into cell walls and the presence of several membranes. While previous studies of protein composition of PD from angiosperms identified large lists of proteins, few were validated. Here, we developed a PD scoring approach in conjunction with systematic localization on a large scale to define a high-confidence PD proteome of Physcomitrium patens. This high confidence PD proteome comprises nearly 300 proteins, which together with the bona fide PD proteins from literature, are made available in the public PDDB database. Conservation of localization across plant species strengthens the reliability of plant PD proteomes and provides a basis for exploring the evolution of this important organelle. In particular, the P. patens PD proteome was highly enriched in cell wall modifying proteins. Callose-degrading glycolyl hydrolase family 17 (GHL17) proteins are presented as an abundant PD protein family with representatives across an evolutionary scale. Exclusively members of the alpha-clade of the GHL17 family are shown to be PD localized and their orthologs occur only in plant species which have developed PD. Members of the EXORDIUM-family and xyloglucan transglycosylases are additional cell-wall located proteins highly abundant in the P. patens PD proteome also showing evolutionary diversification of PD localized family members from other clade members.

plant biology↗

bioRxiv2022

A conserved enzyme of smut fungi facilitates cell-to-cell movement in the plant bundle sheath

The smut fungi are one of the largest groups of fungal plant pathogens, causing disease in all cereal crops. They directly penetrate their hosts and establish a biotrophic interaction. During colonization of the plant, smut fungi secrete a wide range of effector proteins, which suppress plant immunity and modulate cellular functions as well as development of the host, thereby determining the pathogens life-style and virulence potential. The conserved effector Erc1 (enzyme required for cell-to-cell movement) contributes to virulence of the corn smut Ustilago maydis in maize leaves, but not on the tassel. Erc1 binds to host cell wall components and has a 1,3-{beta}-glucanase activity, which is required to attenuate {beta}-glucan-induced defense responses in host leaves. Confocal microscopy revealed that Erc1 has a cell type-specific virulence function, being necessary for fungal cell-to-cell movement in the plant bundle sheath. This cell type-specific virulence function of Erc1 is fully conserved in the barley pathogen Ustilago hordei, which has a functionally conserved Erc1 orthologue. Thus, Erc1 is an enzymatically active core virulence factor with a cell type-specific virulence function in different hosts, which is important for cell-to-cell movement during host colonization of pathogenic smut fungi.

plant biology↗

bioRxiv2022

PD1+ T-cells correlate with Nerve Fiber Density as a prognostic biomarker in patients with resected perihilar cholangiocarcinoma.

Background & AimsPerihilar cholangiocarcinoma (pCCA) is a rare hepatobiliary malignancy. Nerve fiber invasion (NFI) shows cancer invading the nerve and is considered an aggressive feature. Nerve fiber density (NFD) consists of small nerve fibers without cancer invasion and is divided into high NFD (high numbers of small nerve fibers) or low NFD (low numbers of small nerve fibers). We aim to explore differences in immune cell populations and survival. MethodsWe applied multiplex immunofluorescence (mIF) on 47 pCCA surgically resected patients and investigated the immune cell composition in the tumor microenvironment (TME) of different nerve fiber phenotypes (NFI, high and low NFD). Extensive group comparison was carried out and the association with overall survival (OS) was assessed. ResultsThe NFI ROI was measured with highest CD68+ macrophage levels among 3 ROIs (NFI compared to tumor free p= 0.016 and to tumor p=0.034). Further, for NFI patients the density of co-inhibitory markers CD8+PD1+ and CD68+PD1+ were more abundant in the tumor rather than NFI ROI (p= 0.004 and p= 0.0029 respectively). Comparison between patients with NFD and NFI groups, the signals of co-expression of CD8+PD1+ as well as CD68+PD1+ were significantly higher in the high NFD group (p= 0.027 and p= 0.044, respectively). The OS for high NFD patients was 92 months median OS (95% CI:41-142), for low NFD patients 20 months ((95% CI: 4-36) and for NFI group of patients 19 months (95% CI 7-33). The OS for high NFD patients was significantly better compared to low NFD (p= 0.046) and NFI (p= 0.032). ConclusionsPD1+ T-cells correlate with high NFD as a prognostic biomarker, the biological pathway behind this needs to be investigated. Lay summaryNerve fibers play a dual role in the tumor microenvironment in pCCA. In our previous study, we showed that the presence of high numbers of small nerve fibers is associated with a better overall survival. In addition, we found that in high NFD patients PD1+ T-cells are significantly overexpressed. Therefore, we present high NFD as a promising prognostic biomarker. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/475344v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@e30fadorg.highwire.dtl.DTLVardef@11a4e4aorg.highwire.dtl.DTLVardef@a04d8org.highwire.dtl.DTLVardef@1c425db_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

Sustained TREM2 stabilization accelerates microglia heterogeneity and Abeta pathology in a mouse model of Alzheimer s disease

TREM2 is a transmembrane protein expressed exclusively in microglia in the brain that regulates inflammatory responses to pathological conditions. Proteolytic cleavage of membrane TREM2 affects microglial function and is associated with Alzheimers disease, but the consequence of reduced TREM2 proteolytic cleavage has not been determined. We generated a transgenic mouse model of reduced TREM2 shedding (Trem2-IPD) through amino acid substitution of ADAM-protease recognition site. We found that Trem2-IPD mice displayed increased TREM2 cell surface receptor load, survival and function in myeloid cells. Using single cell transcriptomic profiling of mouse cortex we show that sustained TREM2 stabilization induces a shift of fate in microglial maturation and accelerates microglial responses to A{beta} pathology in a mouse model of Alzheimers disease. Our data indicate that reduction of TREM2 proteolytic cleavage aggravates neuroinflammation during the course of AD pathology suggesting that TREM2 shedding is a critical regulator of microglial activity in pathological states.

neuroscience↗

bioRxiv2020

The Ustilago hordei-barley interaction is a versatile system to characterize fungal effectors

Obligate biotrophic fungal pathogens, such as Blumeria graminis and Puccinia graminis, are amongst the most devastating plant pathogens, causing dramatic yield losses in many economically important crops worldwide. However, a lack of reliable tools for the efficient genetic transformation has hampered studies into the molecular basis of their virulence/pathogenicity. In this study, we present the U. hordei-barley pathosystem as a model to characterize effectors from different plant pathogenic fungi. We have generated U. hordei solopathogenic strains, which form infectious filaments without presence of compatible mating partner. Solopathogenic strains are suitable as heterologous expression system for fungal virulence factors. A highly efficient Crispr/Cas9 gene editing system is made available for U. hordei. In addition, U. hordei infection structures during barley colonization were analyzed by transmission electron microscopy, which shows that U. hordei forms intracellular infection structures sharing high similarity to haustoria formed by obligate rust and powdery mildew fungi. Thus, U. hordei has high potential as a fungal expression platform for functional studies of heterologous effector proteins in barley.

plant biology↗

bioRxiv2019

Flowering behaviour in Arabis alpina ensures the maintenance of a perennating dormant bud bank

Arabis alpina, similar to woody perennials, has a complex architecture with a zone of axillary vegetative branches and a zone of dormant buds that serve as perennating organs. We show that floral development during vernalization is the key for shaping the dormant bud zone by facilitating a synchronized and rapid growth after vernalization and thereby causing an increase in auxin response and transport and endogenous indole-3-acetic acid (IAA) levels in the stem. Floral development during vernalization is associated with the development of axillary buds in subapical nodes. Our transcriptome analysis indicated that these buds are not dormant during vernalization but only attain sustained growth after the return to warm temperatures. Floral and subapical vegetative branches grow after vernalization and inhibit the development of the buds below. Dormancy in these buds is regulated across the A. alpina life cycle by low temperatures and by apical dominance in a BRANCHED 1-dependent mechanism.

plant biology↗