Biology subjects

Dagvadorj, B.

Publications and source records attributed to Dagvadorj, B..

8 recordsLinked to original sources

bioRxiv2026

Direct effector recognition by a tandem kinase triggers non-canonical immunity in wheat

Tandem kinase proteins (TKPs) are an important class of disease resistance genes in cereal crops alongside nucleotide-binding (NB-ARC) leucine-rich repeat (LRR) (NLR) receptors. Here, we cloned the wheat (Triticum aestivum) resistance gene Lr41, which encodes a TKP with a C-terminal fusion, and its paired effector gene AvrLr41 from the rust pathogen Puccinia triticina. AvrLr41 is unusually large and highly divergent from most fungal effectors and is directly recognized by Lr41 through its pseudokinase domain. Immune activation mediated by Lr41 require auxiliary helper proteins, including either a minimal coiled-coil (CC) helper protein or its full-length NLR ortholog. These findings reveal a non-canonical immune system in which a kinase-type receptor directly recognizes an effector and recruits either CC or NLR helpers, demonstrating that full-length NLRs are not strictly required for NLR-linked immune execution and expanding the functional repertoire of disease resistance proteins in crops.

plant biology↗

bioRxiv2025

A conserved stripe rust effector elicits variable resistance responses in wheat

Plant resistance (R) and pathogen avirulence (Avr) gene interactions are central to pathogen recognition and disease resistance in crops. Functional characterisation of recognised Avr effectors of Puccinia striiformis f. sp. tritici (Pst) lags other key fungal pathogens of wheat. Here, we used a wheat protoplast-based screen to identify Avr/R interactions via the proxy of effector-induced defence responses in a set of diverse wheat cultivars. We identified an Avr candidate, termed AvrPstB48, that triggers defence responses in 16 out of 24 cultivars tested. AvrPstB48 is hemizygous, and the Pst genome carries four divergent paralogs within a gene cluster. Analysis of these paralogs revealed partial redundancy in their ability to activate wheat defences and enabled us to identify a single amino acid in AvrPstB48 that is necessary but not sufficient for defence activation. Notably, the activation of defence signalling by AvrPstB48 in protoplasts did not directly correlate with disease outcomes. Whole-plant infection assays revealed that some cultivars which exhibited strong defence activation in the protoplast assay are susceptible to the Pst isolate Pst104E137A- from which AvrPstB48 is derived. Comparison of infection dynamics of two wheat cultivars that differ in their AvrPstB48 recognition capacity revealed a delay in disease progression in the recognising cultivar Avocet S compared to the non-recognising cultivar Morocco. While correlative only, our observations, combined with other recent reports, support a recognize-then-suppress model of plant-pathogen interaction where disease outcomes are driven not only by simple Avr/R interactions but also by pathogen effectors that suppress defence signalling downstream of effector recognition.

plant biology↗

bioRxiv2023

Multiplexed effector screening for recognition by endogenous resistance genes using positive defense reporters in wheat protoplasts

O_LIPlant resistance (R) and pathogen avirulence (Avr) gene interactions play a vital role in pathogen resistance. Efficient molecular screening tools for crops lack far behind their model organism counterparts, yet they are essential to rapidly identify agriculturally important molecular interactions that trigger host resistance. C_LIO_LIHere, we have developed a novel wheat protoplast assay that enables efficient screening of Avr/R interactions at scale. Our assay allows access to the extensive gene pool of phenotypically described R genes because it does not require the overexpression of cloned R genes. It is suitable for multiplexed Avr screening, with interactions tested in pools of up to fifty Avr candidates. C_LIO_LIWe identified Avr/R-induced defense genes to create promoter-luciferase reporter. Then, we combined this with a dual-color ratiometric reporter system that normalizes read-outs accounting for experimental variability and Avr/R-induced cell-death. Moreover, we introduced a self-replicative plasmid reducing the amount of plasmid used in the assay. C_LIO_LIOur assay increases the throughput of Avr candidate screening, accelerating the study of cellular defense signaling and resistance gene identification in wheat. We anticipate that our assay will significantly accelerate Avr identification for many wheat pathogens, leading to improved genome-guided pathogen surveillance and breeding of disease-resistant crops. C_LI

plant biology↗

bioRxiv2021

The necrotrophic effector ToxA from Parastagonospora nodorum interacts with wheat NHL proteins to facilitate Tsn1-mediated necrosis

The plant pathogen Parastagonospora nodorum secretes necrotrophic effectors to promote disease. These effectors induce cell death on wheat cultivars carrying dominant susceptibility genes in an inverse gene-for-gene manner. However, the molecular mechanisms underpinning these interactions and resulting cell death remain unclear. Here, we used a yeast-two-hybrid library approach to identify wheat proteins that interact with the necrotrophic effector ToxA. Using this strategy, we identified an interaction between ToxA and a wheat transmembrane NDR/HIN1-like protein (TaNHL10) and confirmed the interaction using in-planta co-immunoprecipitation and confocal microscopy co-localization analysis. We showed that the C-terminus of TaNHL10 is extracellular whilst the N-terminus was localized in the cytoplasm. Further analyses using yeast-two-hybrid and confocal microscopy co-localization showed that ToxA interacts with the C-terminal LEA2 extracellular domain of TaNHL10. Random mutagenesis was then used to identify a ToxA mutant, ToxAN109D, which was unable to interact with TaNHL10 in yeast-two-hybrid assays. Subsequent heterologous expression and purification of ToxAN109D in Nicotiania benthamiana revealed that the mutated protein was unable to induce necrosis on Tsn1-dominant wheat cultivars confirming that the interaction of ToxA with TaNHL10 is required to induce cell death. Collectively, these data advance our understanding on how ToxA induces cell death during infection and further highlights the importance of host cell surface interactions in necrotrophic pathosystems.

plant biology↗

bioRxiv2021

Simple and efficient heterologous expression of necrosis-inducing effectors using the model plant Nicotiana benthamiana

Plant fungal pathogens cause devastating diseases on cereal plants and threaten global food security. During infection, these pathogens secrete proteinaceous effectors that promote disease. Some of these effectors from necrotrophic plant pathogens induce a cell death response (necrosis), which facilitates pathogen growth in planta. Characterisation of these effectors typically requires heterologous expression and microbial expression systems such as bacteria and yeast are the predominantly used. However, microbial expression systems often require optimization for any given effector and are, in general, not suitable for effectors involving cysteine bridges and posttranslational modifications for activity. Here, we describe a simple and efficient method for expressing such effectors in the model plant Nicotiana benthamiana. Briefly, an effector protein is transiently expressed and secreted into the apoplast of N. benthamiana by Agrobacterium-mediated infiltration. Two-to-three days subsequent to agroinfiltration, the apoplast from the infiltrated leaves is extracted and can be directly used for phenotyping on host plants. The efficacy of this approach was demonstrated by expressing the ToxA, Tox3 and Tox1 necrosis-inducing effectors from Parastagonospora nodorum. All three effectors produced in N. benthamiana were capable of inducing necrosis in wheat lines, and two of three showed visible bands on Coomassie-stained gel. These data suggest that N. benthamiana-agroinfiltration system is a feasible tool to obtain fungal effectors, especially those that require disulfide bonds and posttranslational modifications. Furthermore, due to the low number of proteins typically observed in the apoplast (compared to intracellular), this simple and high-throughput approach circumvents the requirement to lyse cells and further purify the target proteins that is required in other heterologous systems. Because of its simplicity and potential for high-throughput, this method is highly amenable to the phenotyping of candidate protein effectors on host plants.

plant biology↗

bioRxiv2020

The crystal structure of SnTox3 from the necrotrophic fungus Parastagonospora nodorum reveals a unique effector fold and insights into Kex2 protease processing of fungal effectors

O_LIPlant pathogens cause disease through secreted effector proteins, which act to modulate host physiology and promote infection. Typically, the sequences of effectors provide little functional information and further targeted experimentation is required. Here, we utilised a structure/function approach to study SnTox3, an effector from the necrotrophic fungal pathogen Parastagonospora nodorum, which causes cell death in wheat-lines carrying the sensitivity gene Snn3. C_LIO_LIWe developed a workflow for the production of SnTox3 in a heterologous host that enabled crystal structure determination. We show this approach can be successfully applied to effectors from other pathogenic fungi. Complementing this, an in-silico study uncovered the prevalence of an expanded subclass of effectors from fungi. C_LIO_LIThe {beta}-barrel fold of SnTox3 is a novel fold among fungal effectors. We demonstrate that SnTox3 is a pre-pro-protein and that the protease Kex2 removes the pro-domain. Our in-silico studies suggest that Kex2-processed pro-domain (designated here as K2PP) effectors are common in fungi, and we demonstrate this experimentally for effectors from Fusarium oxysporum f sp. lycopersici. C_LIO_LIWe propose that K2PP effectors are highly prevalent among fungal effectors. The identification and classification of K2PP effectors has broad implications for the approaches used to study their function in fungal virulence. C_LI

plant biology↗

bioRxiv2020

The Irish potato famine pathogen subverts host vesicle trafficking to channel starvation-induced autophagy to the pathogen interface

Eukaryotic cells deploy autophagy to eliminate invading microbes. In turn, pathogens have evolved effector proteins to counteract antimicrobial autophagy. How and why adapted pathogens co-opt autophagy for their own benefit is poorly understood. The Irish famine pathogen Phythophthora infestans secretes the effector protein PexRD54 that selectively activates an unknown plant autophagy pathway, while antagonizing antimicrobial autophagy. Here we show that PexRD54 induces autophagosome formation by bridging small GTPase Rab8a-decorated vesicles with autophagic compartments labelled by the core autophagy protein ATG8CL. Rab8a is required for pathogen-triggered and starvation-induced but not antimicrobial autophagy, revealing that specific trafficking pathways underpin selective autophagy. We discovered that Rab8a contributes to basal immunity against P. infestans, but PexRD54 diverts a sub-population of Rab8a vesicles to lipid droplets that associate with autophagosomes. These are then diverted towards pathogen feeding structures that are accommodated within the host cells. We propose that PexRD54 mimics starvation-induced autophagy by channeling host endomembrane trafficking towards the pathogen interface possibly to acquire nutrients. This work reveals that effectors can interconnect independent host compartments to stimulate complex cellular processes that benefit the pathogen. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/000117v1_ufig1.gif" ALT="Figure 1"> View larger version (83K): org.highwire.dtl.DTLVardef@bfc9fforg.highwire.dtl.DTLVardef@166b5f8org.highwire.dtl.DTLVardef@34d581org.highwire.dtl.DTLVardef@ad397f_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2020

In-depth secretome analysis of Puccinia striiformis f. sp. tritici in infected wheat uncovers effector functions

The importance of wheat yellow rust disease, caused by Puccinia striiformis f. sp. tritici (Pst), has increased substantially due to the emergence of aggressive new Pst races in the last couple of decades. In an era of escalating human populations and climate change, it is vital to understand the infection mechanism of Pst in order to develop better strategies to combat wheat yellow disease. This study focuses on the identification of small secreted proteins (SSPs) and candidate-secreted effector proteins (CSEPs) that are used by the pathogen to support infection and control disease development. We generated de novo assembled transcriptomes of Pst collected from wheat fields in central Anatolia. We inoculated both susceptible and resistant seedlings with Pst and analyzed haustoria formation. At 10 days post-inoculation (dpi), we analyzed the transcriptomes and identified 10,550 Differentially Expressed Unigenes (DEGs), of which 6,220 were Pst-related. Among those Pst-related genes, 230 were predicted as PstSSPs. In silico characterization was performed using an approach combining the transcriptomic data and data mining results to provide a reliable list to narrow down the ever-expanding repertoire of predicted effectorome. The comprehensive analysis detected 14 Differentially Expressed Small-Secreted Proteins (DESSPs) that overlapped with the genes in available literature data to serve as the best CSEPs for experimental validation. One of the CSEPs was cloned and studied to test the reliability of the presented data. Biological assays show that the randomly selected CSEP, Unigene17495 (PSTG_10917), localizes in the chloroplast and is able to suppress cell death induced by INF1 in a Nicotiana benthamiana heterologous expression system.

microbiology↗