Biology subjects

Bautor, J.

Publications and source records attributed to Bautor, J..

9 recordsLinked to original sources

bioRxiv2026

Arabidopsis cysteine protease RD19 limits RBOHD-generated ROS production in pattern triggered immunity

Plants perceive pathogenic threats through receptors localized at the plasma membrane and inside cells to initiate pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), respectively. PTI and ETI pathways are interconnected and partially converge on the EDS1-PAD4-ADR1 branch which stimulates anti-pathogen defence. Besides these canonical immune pathways, proteolysis plays a pivotal role in immunity by regulating the abundance and activities of diverse components. We previously identified Arabidopsis papain-like cysteine protease RD19 as a PAD4 interactor and showed that RD19 promotes resistance to host-adapted pathogens. Here, we investigated the contribution of RD19 to bacterial flg22 and nlp20 elicited PTI responses which exhibit, respectively, partial and high PAD4 dependence. We show that although PAD4 and RD19 both promote PTI, they have separate functions. In resting (non-triggered) and nlp20-triggered tissues, RD19 limits RBOHD protein accumulation and consequently ROS production. Using N-terminomic enrichment and protease cleavage site identification methods we identify candidate RD19 substrates in resting and nlp20-responding tissues. Our analysis shows that two immune-related aspartyl proteases AED3 and AED2/ASPG1 are likely direct RD19 targets. This study reveals a role of RD19 in ROS regulation and advances our understanding of proteolysis and dynamic RD19 substrate targeting in plant immunity.

plant biology↗

bioRxiv2026

Conserved TIR-only proteins drive transcriptional defense and basal immunity in dicot and monocot plants

Toll/interleukin-1/resistance (TIR) domain NADase enzymes signal in plant immunity by producing ribosylated nucleotide second messengers which activate EDS1 dimer-helper NLR pathways to restrict pathogen growth. Members of a small, distinctive group of TIR-only proteins are conserved between dicots and monocots, yet their functions remain poorly understood. Here, we show that conserved TIR-only proteins in Arabidopsis and barley share a fundamental enzymatic role in promoting basal defense against virulent filamentous pathogens, independently of NLR mediated effector-triggered immunity. Metabolite analysis of transiently expressed Arabidopsis and barley TIR-only proteins revealed their capacity to produce ribosylated cyclic nucleotides in vivo. By comparing phenotypes of tir-only and eds1 pad4 CRISPR mutants in the two species, as well as adr1 mutants in barley, we established that the TIR-only proteins promote PAMP-triggered transcriptional defenses associated with pathogen restriction. Barley possesses just one essential TIR-only enzyme and mutations of the two conserved TIR-only members in Arabidopsis were not compensated for by numerous other TIR-domain genes in the basal immune response. These findings suggest that conserved TIR-only proteins make a crucial contribution to TIR basal defense signaling networks of Arabidopsis and barley. We propose that a shared function in transcriptional defense regulation could explain the evolutionary retention of this discrete TIR-only group across monocot and dicot lineages.

plant biology↗

bioRxiv2025

GH25 lysozyme mediates tripartite interkingdom interactions and microbial competition on the plant leaf surface

Microbial communities inhabiting plants have emerged as crucial factors in regulating plant health and defense against disease-causing pathogens. The basidiomycete yeast Moesziomyces bullatus ex. Albugo on Arabidopsis (MbA) releases Glycoside Hydrolase 25 (GH25) protein which regulates the leaf microbiome by antagonizing an oomycete A. laibachii biotrophic pathogen MbA. Application of both MbA and GH25 protein rescued fresh shoot weight of A. thaliana upon A. laibachii infection, showing its potential in plant protection. Tripartite interaction assays did not reveal antagonistic activity of GH25 towards other plant pathogenic oomycetes or fungi besides A. laibachii. We identified a core set of bacteria are closely associated with A. laibachii and established that GH25 inhibits members of this core group. Among A. laibachii-associated bacteria that were inhibited by GH25, Curtobacterium sp. could override the inhibition of A. laibachii by MbA. We describe a tripartite antagonistic interaction in which bacterium and oomycete protect each other from growth inhibition by MbA. Curtobacterium sp., in turn, exhibits specific inhibition of A. laibachii-associated bacteria that are not targeted by MbA but themselves antagonize A. laibachii. Our study reveals an inter-kingdom interaction network in which a GH25 lysozyme shapes the antagonistic relationship between yeast, a pathogenic oomycete and an oomycete-associated bacterium.

microbiology↗

bioRxiv2021

Arabidopsis Topless-related 1 mitigates physiological damage and growth penalties of induced immunity

Transcriptional corepressors of the Topless family are important regulators of plant hormone and immunity signaling. The lack of a genome-wide profile of their chromatin associations limits understanding of transcriptional regulation in plant immune responses. Chromatin immunoprecipitation with sequencing (ChIP-seq) was performed on GFP-tagged Topless-related 1 (TPR1) expressed in Arabidopsis thaliana lines with and without constitutive immunity dependent on Enhanced Disease Susceptibility 1 (EDS1). RNA-seq profiling of pathogen-infected tpl/tpr mutants and assessments of growth and physiological parameters were employed to determine TPL/TPR roles in transcriptional immunity and defense homeostasis. TPR1 bound to promoter regions of ~1,400 genes and ~10% of the detected binding required EDS1 immunity signaling. A tpr1 tpl tpr4 (t3) mutant displayed mildly enhanced defense-related transcriptional reprogramming upon bacterial infection but not increased bacterial resistance. Bacteria or pep1 phytocytokine-challenged t3 plants exhibited, respectively, photosystem II dysfunction and exacerbated root growth inhibition. Transgenic expression of TPR1 restored the t3 physiological defects. We propose that TPR1 and TPL-family proteins function in Arabidopsis to reduce detrimental effects associated with activated transcriptional immunity.

plant biology↗

bioRxiv2020

Pathogen effector recognition-dependent association of NRG1 with EDS1 and SAG101 in TNL receptor immunity

Plants utilise intracellular nucleotide-binding, leucine-rich repeat (NLR) immune receptors to detect pathogen effectors and activate local and systemic defence. NRG1 and ADR1 "helper" NLRs (RNLs), cooperate with enhanced disease susceptibility 1 (EDS1), senescence-associated gene 101 (SAG101) and phytoalexin-deficient 4 (PAD4) lipase-like proteins to mediate signalling from TIR domain NLR receptors (TNLs). However, the mechanism of RNL/EDS1-family protein cooperation is poorly understood. Here, we provide genetic and molecular evidence for exclusive EDS1/SAG101/NRG1 and EDS1/PAD4/ADR1 co-functions in TNL immunity. Using immunoprecipitation and mass spectrometry, we show effector recognition-dependent association of NRG1 with EDS1 and SAG101, but not PAD4. An EDS1-SAG101 complex associates with NRG1, and EDS1-PAD4 associates with ADR1, only in an immune-activated state. NRG1 requires an intact nucleotide-binding P-loop motif, and EDS1 a functional EP domain and its partner SAG101, for induced association and immunity. Thus, two distinct modules (NRG1/EDS1/SAG101 and ADR1/EDS1/PAD4) are required to execute TNL receptor defence signalling.

plant biology↗

bioRxiv2019

Arabidopsis ENHANCED DISEASE RESISTANCE1 Protein Kinase Regulates the Association of ENHANCED DISEASE SUSCEPTIBILITY1 and PHYTOALEXIN DEFICIENT4 to Inhibit Cell Death

ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4) are sequence-related lipase-like proteins that function as a complex to regulate defense responses in Arabidopsis by both salicylic acid-dependent and independent pathways. Here we describe a gain-of-function mutation in PAD4 (S135F) that enhances resistance and cell death in response to infection by the powdery mildew pathogen Golovinomyces cichoracearum. The mutant PAD4 protein accumulates to wild-type levels in Arabidopsis cells, thus these phenotypes are unlikely to be due to PAD4 over accumulation. The phenotypes are similar to loss of function mutations in the protein kinase Enhanced Disease Resistance1 (EDR1), and previous work has shown that loss of PAD4 or EDS1 suppresses edr1-mediated phenotypes, placing these proteins downstream of EDR1. Here we show that EDR1 directly associates with EDS1 and PAD4 and inhibits their interaction in yeast and plant cells. We propose a model whereby EDR1 negatively regulates defense responses by interfering with the heteromeric association of EDS1 and PAD4. Our data indicate that the S135F mutation likely alters an EDS1-independent function of PAD4, potentially shedding light on a yet unknown PAD4 signaling function.

plant biology↗

bioRxiv2019

Arabidopsis thaliana natural variation in temperature-modulated immunity uncovers transcription factor UNE12 as a thermoresponsive regulator

Temperature impacts plant immunity and growth but how temperature intersects with endogenous pathways remains unclear. Here we uncover variation between Arabidopsis thaliana natural accessions in response to two non-stress temperatures (22{degrees}C and 16{degrees}C) affecting accumulation of the thermoresponsive stress hormone salicylic acid (SA) and plant growth. Analysis of differentially responding A. thaliana accessions shows that pre-existing SA provides a benefit in limiting bacterial pathogen infection at both temperatures. Several A. thaliana genotypes display a capacity to mitigate negative effects of high SA on growth, indicating within-species plasticity in SA - growth tradeoffs. An association study of temperature x SA variation, followed by physiological and immunity phenotyping of mutant and over-expression lines, identifies the transcription factor unfertilized embryo sac 12 (UNE12) as a temperature-responsive SA immunity regulator. Here we reveal previously untapped diversity in plant responses to temperature and a way forward in understanding the genetic architecture of plant adaptation to changing environments.

plant biology↗

bioRxiv2019

A coevolved EDS1-SAG101-NRG1 module mediates cell death signaling by TIR-domain immune receptors

Plant intracellular nucleotide-binding/leucine-rich repeat (NLR) immune receptors are activated by pathogen effectors to trigger host defenses and cell death. Toll-Interleukin1-receptor (TIR)-domain NLRs (TNLs) converge on the Enhanced Disease Susceptibility1 (EDS1) family of lipase-like proteins for all resistance outputs. In Arabidopsis TNL immunity, AtEDS1 heterodimers with Phytoalexin Deficient4 (AtPAD4) transcriptionally boost basal defense pathways. AtEDS1 uses the same surface to interact with PAD4-related Senescence-Associated Gene101 (AtSAG101), but the role of AtEDS1-AtSAG101 heterodimers was unclear. We show that AtEDS1-AtSAG101 function together with AtNRG1 coiled-coil domain helper NLRs as a coevolved TNL cell death signaling module. AtEDS1-AtSAG101-AtNRG1 cell death activity is transferable to the solanaceous species, Nicotiana benthamiana, and cannot be substituted by AtEDS1-AtPAD4 with AtNRG1 or AtEDS1-AtSAG101 with endogenous NbNRG1. Analysis of EDS1-family evolutionary rate variation and heterodimer structure-guided phenotyping of AtEDS1 variants or AtPAD4-AtSAG101 chimeras identify closely aligned -helical coil surfaces in the AtEDS1-AtSAG101 partner C-terminal domains that are necessary for TNL cell death signaling. Our data suggest that TNL-triggered cell death and pathogen growth restriction are determined by distinctive features of EDS1-SAG101 and EDS1-PAD4 complexes and that these signaling machineries coevolved with further components within plant species or clades to regulate downstream pathways in TNL immunity.

plant biology↗

bioRxiv2018

An EDS1 EP-domain surface mediating timely transcriptional reprogramming of immunity genes

Plant intracellular NLR receptors recognize pathogen interference to trigger immunity. NLR signalling mechanisms have not been resolved. Enhanced disease susceptibility 1 (EDS1) heterodimers are recruited by Toll-interleukin1-receptor domain NLRs (TNLs) to transcriptionally mobilize resistance pathways. Using an Arabidopsis EDS1 heterodimer crystal structure we interrogate the conserved but functionally uncharacterized EDS1 -helical EP-domain. We identify EP-domain positively charged residues lining a cavity that are essential for TNL immunity signalling, beyond heterodimer formation. Mutating arginine (R493) to alanine creates a weak EDS1 allele which disables TNL immunity against bacteria producing a virulence factor, coronatine (COR). Arabidopsis plants expressing EDS1R493A are slow to mobilize defence gene expression changes, independently of COR. The transcriptional delay has severe consequences for pathogen resistance and for countering bacterial COR. We uncover a set of host immunity genes whose repression by COR is blocked by wild-type EDS1 but not by EDS1R493A in the TNL response. These data uncover an EDS1 signalling surface lining the heterodimer EP-domain cavity which confers timely transcriptional reprogramming of host defence pathways and blocks bacterial virulence in NLR receptor immunity.

plant biology↗