Biology subjects

Ngou, B. P. M.

Publications and source records attributed to Ngou, B. P. M..

10 recordsLinked to original sources

bioRxiv2025

Uncoupling hypersensitive cell death response and disease resistance activated by effector-triggered immunity

Effector-triggered immunity (ETI) is a major defence strategy in plants and is frequently associated with the hypersensitive response (HR), a localized form of programmed cell death long assumed to be essential for pathogen resistance. However, the causal relationship between HR and effective immunity remains unresolved. We show that the Arabidopsis cbp60g sard1 double mutant exhibits exaggerated ETI-associated HR but only partial resistance to bacterial and oomycete pathogens, thereby genetically uncoupling cell death from disease resistance without pleiotropic defects. Genome-wide transcriptome profiling reveals that the absence of CBP60g and SARD1 disrupts the balance between immune activators and suppressors, including reduced induction of the Nudix hydrolase NUDT7. Overexpression of NUDT7 diminishes but does not abolish the heightened HR phenotype in cbp60g sard1 mutant, indicating that multiple negative regulators act redundantly to restrain immune-associated cell death. These findings demonstrate that HR is not an obligatory determinant of effective resistance and provide mechanistic insight into how plants coordinate transcriptional networks to balance pathogen defence with the containment of host cell death. By refining the relationship between HR and immunity, this work challenges a long-standing paradigm in plant biology and advances our understanding of immune regulation.

plant biology↗

bioRxiv2025

Systematic Discovery and Design of Synthetic Immune Receptors in Plants

Plants deploy a diverse array of pattern recognition receptors (PRRs) that perceive microbe-associated molecular patterns (MAMPs) to activate immune responses. Leucine-rich repeat receptor-like kinase subgroup XII (LRR-RLK-XII) represents one of the largest PRR families due to lineage-specific diversification. Bioinformatics, synthetic biology, and biochemical approaches were integrated to characterize PRRs from 285 plant species. We identified a receptor, named "SCORE", that perceives cold-shock protein (CSP) peptides. SCORE orthologs from multiple angiosperm lineages exhibit remarkable CSP recognition polymorphisms, indicating recurrent selection for pathogen recognition through substitutions at key amino acid residues. Through functional phylogenomics and protein structure predictions, we generated synthetic SCORE variants capable of detecting multiple phytopathogen CSP peptides, thus revealing the diverse PRR recognition landscape in plants. Our strategy hold promises for engineering plant immune receptors, particularly for perennial crops.

plant biology↗

bioRxiv2025

A trehalase-derived MAMP triggers LecRK-V-mediated immune responses in Arabidopsis

Plant-parasitic nematodes (PPNs) cause major agricultural losses worldwide, yet the molecular basis of plant immunity against these pathogens remains poorly understood. To investigate how plants recognize PPNs, we aimed to identify microbe-associated molecular patterns (MAMPs) from nematodes and the corresponding plant immune components. Due to the limited availability of material from obligate PPNs, we used Caenorhabditis elegans, a free-living nematode, as a MAMP source. C. elegans extracts activated MAMP-triggered immune responses in Arabidopsis Col-0. Through chromatography-based purification, we identified a secreted trehalase and pinpointed a conserved peptide region essential for its MAMP activity. A corresponding peptide from root-knot nematode trehalase enabled the identification of lectin receptor kinases LecRK-V.5 and LecRK-V.6 as key components in immune induction. Notably, this peptide region is conserved across insect and fungal pathogens, with LecRK-Vs required for immune responses to these peptides, highlighting the role of LecRK-V-mediated mechanism for broad-spectrum pathogen detection via trehalase-derived peptides. TeaserTrehalase-derived peptides trigger LecRK-V-mediated immune responses in plants, enabling broad detection of nematodes, insects, and fungi.

plant biology↗

bioRxiv2023

Evolutionary Trajectory of Pattern Recognition Receptors in Plants

Plants perceive pathogen-associated molecular patterns (PAMPs) via pattern recognition receptors (PRRs) to activate PRR-triggered immunity (PTI). Despite extensive research on PTI in model plant species, the evolutionary trajectory and emergence of PRRs remain elusive. Here we conducted a comparative genomic analysis of cell-surface receptors and downstream signalling components among 350 plant species. Our findings reveal that cell-surface receptors comprise two major classes, receptor-like proteins (RLPs) and receptor-like kinases (RLKs), with RLP being more ancient whereas RLK families have undergone significant expansion. We also demonstrate that multiple downstream signalling components have an ancient origin within the plant lineage. To shed light on the immune-specificity of PRRs, we traced the evolutionary origin of immune-specific leucine-rich repeat-RLPs (LRR-RLPs) in plants. Surprisingly, we discovered that the last four LRR motifs crucial for co-receptor interaction in LRR-RLPs are closely related to those of the LRR-RLK subgroup Xb, which primarily governs growth and development. Functional characterisation further reveals that LRR-RLPs initiate immune responses through their juxtamembrane and transmembrane regions, while LRR-RLK-Xb members regulate development through their cytosolic kinase domains. Our data suggest modular evolution of cell-surface receptors in which immunity- and development-specific cell-surface receptors share a common origin. After diversification, their ectodomains, juxtamembrane, transmembrane, and cytosolic regions have either diversified or stabilised to recognize ligands that activate different downstream responses. We propose that cell-surface receptors and downstream signalling components are ancient, and likely predate the emergence of land plants, subsequently evolving to exhibit greater complexity and specificity within the land plant lineage.

plant biology↗

bioRxiv2022

Oligomerisation of a plant helper NLR requires cell-surface and intracellular immune receptor activation

Plant disease resistance involves both detection of microbial molecular patterns by cell-surface pattern recognition receptors and detection of pathogen effectors by intracellular NLR immune receptors. NLRs are classified as sensor NLRs, involved in effector detection, or helper NLRs required for sensor NLR signalling. TIR-domain-containing sensor NLRs (TNLs) require helper NLRs NRG1 and ADR1 for resistance, and their activation of defense also requires the lipase-domain proteins EDS1, SAG101 and PAD4. We investigated how the helper NLR NRG1 supports TNL-initiated immunity with EDS1 and SAG101. We find that NRG1 associates with EDS1 and SAG101 at the plasma membrane and in the nucleus, but only self-associates at the plasma membrane. Activation of TNLs is sufficient to trigger NRG1-EDS1-SAG101 interaction, but cell-surface receptor-initiated defense is also required to form an oligomeric Resistosome. The data point to formation of NRG1-EDS1-SAG101 heterotrimers in the nucleus upon intracellular receptor activation alone and indicate formation of NRG1-EDS1-SAG101 Resistosomes at the plasma membrane upon co-activation of intracellular and cell surface-receptor pathways.

plant biology↗

bioRxiv2022

Concerted expansion and contraction of immune receptor gene repertoires in plant genomes

Recent reports suggest that cell-surface and intracellular immune receptors function synergistically to activate robust defence against pathogens, but whether or not they co-evolve is unclear. Here we determined the copy numbers of cell-surface and intracellular immune receptors in 208 species. Surprisingly, these receptor gene families contract and/or expand together in plant genomes, suggesting the mutual potentiation of immunity initiated by cell-surface and intracellular receptors is reflected in the concerted co-evolution of the size of their repertoires across plant species.

plant biology↗

bioRxiv2020

Chromatin accessibility landscapes activated by cell surface and intracellular immune receptors

Activation of cell Surface and Intracellular Receptor-Mediated Immunity (SRMI and IRMI) results in rapid transcriptional reprogramming that underpins disease resistance. However, the mechanisms by which SRMI and IRMI lead to transcriptional changes are not clear. Here, we combine RNA-seq and ATAC-seq to define changes in gene expression and chromatin accessibility; both SRMI and IRMI increase chromatin accessibility at induced defense genes. Analysis of ATAC-seq and RNA-seq data combined with publicly available information on transcription factor DNA-binding motifs enabled comparison of individual gene regulatory networks activated by SRMI and IRMI, and by both. These results and analyses reveal overlapping and conserved transcriptional regulatory mechanism between the two immune systems.

plant biology↗

bioRxiv2020

Mutual Potentiation of Plant Immunity by Cell-surface and Intracellular Receptors

The plant immune system involves cell-surface receptors that detect intercellular pathogen-derived molecules, and intracellular receptors that activate immunity upon detection of pathogen-secreted effectors that act inside the plant cell. Surface receptor-mediated immunity has been extensively studied but in authentic interactions between plants and microbial pathogens, its presence impedes study of intracellular receptor-mediated immunity alone. How these two immune pathways interact is poorly understood. Here, we reveal mutual potentiation between these two recognition-dependent defense pathways. Recognition by surface receptors activates multiple protein kinases and NADPH oxidases, whereas intracellular receptors primarily elevate abundance of these proteins. Reciprocally, the intracellular receptor-dependent hypersensitive cell death response is strongly enhanced by activation of surface receptors. Activation of either immune system alone is insufficient to provide effective resistance against Pseudomonas syringae. Thus, immune pathways activated by cell-surface and intracellular receptors mutually potentiate to activate strong defense that thwarts pathogens. By studying the activation of intracellular receptors in the absence of surface receptor-mediated immunity, we have dissected the relationship between the two distinct immune systems. These findings reshape our understanding of plant immunity and have broad implications for crop improvement.

plant biology↗

bioRxiv2019

High-resolution Expression Profiling of Selected Gene Sets during Plant Immune Activation

Sequence capture followed by next-generation sequencing has broad applications in cost-effective exploration of biological processes at high resolution [1, 2]. Genome-wide RNA sequencing (RNA-seq) over a time course can reveal the dynamics of differential gene expression. However, in many cases, only a limited set of genes are of interest, and are repeatedly used as markers for certain biological processes. Sequence capture can help generate high-resolution quantitative datasets to assess changes in abundance of selected genes. We previously used sequence capture to accelerate Resistance gene cloning [1, 3, 4], investigate immune receptor gene diversity [5] and investigate pathogen diversity and evolution [6, 7].\n\nThe plant immune system involves detection of pathogens via both cell-surface and intracellular receptors. Both receptor classes can induce transcriptional reprogramming that elevates disease resistance [8]. To assess differential gene expression during plant immunity, we developed and deployed quantitative sequence capture (CAP-I). We designed and synthesized biotinylated single-strand RNA bait libraries targeted to a subset of defense genes, and generated sequence capture data from 99 RNA-seq libraries. We built a data processing pipeline to quantify the RNA-CAP-I-seq data, and visualize differential gene expression. Sequence capture in combination with quantitative RNA-seq enabled cost-effective assessment of the expression profile of a specified subset of genes. Quantitative sequence capture is not limited to RNA-seq or any specific organism and can potentially be incorporated into automated platforms for high-throughput sequencing.

plant biology↗

bioRxiv2019

Estradiol-inducible AvrRps4 expression reveals distinct properties of TIR-NLR-mediated effector-triggered immunity

Plant nucleotide-binding domain, leucine-rich repeat receptor (NLR) proteins play important roles in recognition of pathogen-derived effectors. However, the mechanism by which plant NLRs activate immunity is still largely unknown. The paired Arabidopsis NLRs RRS1-R and RPS4, that confer recognition of bacterial effectors AvrRps4 and PopP2, are well studied, but how the RRS1/RPS4 complex activates early immediate downstream responses upon effector detection is still poorly understood. To study RRS1/RPS4 responses without the influence of cell-surface receptor immune pathways, we generated an Arabidopsis line with inducible expression of effector AvrRps4. Induction does not lead to hypersensitive cell death response (HR) but can induce electrolyte leakage, which often correlates with plant cell death. Activation of RRS1 and RPS4 without pathogens cannot activate mitogen-associated protein kinase cascades, but still activates upregulation of defense genes, and therefore resistance against bacteria.\n\nHighlightInducible expression of AvrRps4 activates RRS1/RPS4-mediated effector-triggered immunity without the presence of pathogens, allowing us to characterise downstream immune responses triggered by TIR-NLRs without cell-surface receptor-mediated immunity.

plant biology↗