scholarly journals Molecular mechanisms of host cell manipulation by plant pathogens

2014 ◽  
Vol 70 (a1) ◽  
pp. C801-C801
Author(s):  
Richard Hughes ◽  
Stuart King ◽  
Abbas Maqbool ◽  
Hazel McLellan ◽  
Tolga Bozkurt ◽  
...  
Keyword(s):  
Cell Death ◽  
Crop Production ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Complex Structure ◽  
Effector Proteins ◽  
Plant Diseases ◽  
Cell Manipulation ◽  
Cell Physiology ◽  
Structural Studies

An estimated 15% of global crop production is lost to pre-harvest disease every year. New ways to manage plant diseases are required. A mechanistic understanding of how plant pathogens re-program their hosts to enable colonisation may provide novel genetic or chemical opportunities to interfere with disease. One notorious plant parasite is the Irish potato famine pathogen Phytophthora infestans. This pathogen remains a considerable threat to potato/tomato crops today as the agent of late blight. Plant pathogens secrete effector proteins outside of and into plant cells to suppress host defences and manipulate cell physiology. Structural studies have provided insights into effector evolution and enabled experiments to probe function [1-3]. Crystal structures of 4 Phytophthora RXLR-type effectors, which are unrelated in primary sequence, revealed similarities in the fold of these proteins. This fold was proposed to act as a stable scaffold that supports diversification of effectors. Further, molecular modelling has enabled mapping of single-site variants responsible for specialisation of a Phytophthora Cystatin-like effector, revealing how effectors can adapt to new hosts after a "host jump". Structural studies describing how RXLR-effectors interact with host targets are lacking. We have used Y2H/co-IP studies to identify host proteins that interact with P. infestans effectors PexRD2 and PexRD54. PexRD2 interacts with MAPKKKe, a component of plant immune signalling pathways, and suppressed cell death activities of this protein. We used the structure of PexRD2 to design mutants that fail to interact with MAPKKKe, and no longer suppress cell-death activities. We found that PexRD54 interacts with potato homologues of the autophagy protein ATG8. We have obtained a crystal structure for PexRD54 in the presence of ATG8. We are now using X-ray scattering to verify the complex structure in solution prior to establishing the role of this interaction during infection.

scholarly journals The actin cytoskeleton mediates transmission of Candidatus Liberibacter solanacearum by the carrot psyllid

2020 ◽  
Author(s):  
Poulami Sarkar ◽  
Svetlana Kontsedalov ◽  
Galina Lebedev ◽  
Murad Ghanim
Keyword(s):  
Actin Cytoskeleton ◽  
Defense Mechanisms ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Plant Diseases ◽  
Citrus Industry ◽  
Citrus Greening Disease ◽  
Associated Diseases ◽  
Novel Approach ◽  
Vector Borne

Several vector-borne plant pathogens have evolved mechanisms to exploit and hijack vector host cellular, molecular and defense mechanisms for their transmission. Over the past few years, Liberibacter species, which are transmitted by several psyllid vectors, have become an economically important group of pathogens that devastated the citrus industry and caused tremendous losses to many other important crops worldwide. The molecular mechanisms underlying the interactions of Liberibacter species with their psyllid vectors are poorly studied. Candidatus Liberibacter solanacearum (CLso) associated with important vegetable diseases is transmitted by the carrot psyllid, Bactericera trigonica in a persistent manner. Here, we elucidated the role of B. trigonica Arp2/3 protein complex, which plays a major role in the regulation of the actin cytoskeleton, in the transmission of CLso. CLso co-localized with ArpC2, a key protein in this complex, and this co-localization strongly associated with actin filaments. Silencing the psyllid ArpC2 disrupted the co-localization and the dynamics of F-actin. Silencing RhoGAP21 and Cdc42, which act in the signaling cascade leading to upregulation of Arp2/3 and F-actin bundling, also showed similar results. On the other hand, silencing ArpC5, another component of the complex, did not induce any significant effects on F-actin formation. Finally, ArpC2 silencing caused 73.4% reduction in CLso transmission by psyllids, strongly suggesting that its transmission by B. trigonica is cytoskeleton-dependent and it interacts with ArpC2 to exploit the intracellular actin nucleation process for transmission. Targeting this unique interaction could lead to developing a novel strategy for the management of Liberibacter-associated diseases. IMPORTANCE Plant diseases caused by vector-borne pathogens are responsible for tremendous losses and threaten some of the most important agricultural crops. A good example is the citrus greening disease caused by bacteria of the genus Liberibacter and transmitted by psyllids, and has devastated the citrus industry in the US, China and Brazil. Here we show that the psyllid-transmitted Candidatus Liberibacter solanacearum (CLso) employs the actin cytoskeleton of psyllid gut cells, specifically the ArpC2 protein in the Arp2/3 complex of this system, for movement and transmission in the vector. Silencing ArpC2 dramatically influenced interaction of CLso with the cytoskeleton and decreased the bacteria transmission to plants. This system could be targeted for developing a novel approach for the control of Liberibacter- associated diseases.

scholarly journals Secretome Analysis and In Planta Expression of Salivary Proteins Identify Candidate Effectors from the Brown Planthopper Nilaparvata lugens

2019 ◽  
Vol 32 (2) ◽  
pp. 227-239 ◽  
Author(s):  
Weiwei Rao ◽  
Xiaohong Zheng ◽  
Bingfang Liu ◽  
Qin Guo ◽  
Jianping Guo ◽  
...  
Keyword(s):  
Cell Death ◽  
Expression Analysis ◽  
Plant Pathogens ◽  
Critical Role ◽  
Brown Planthopper ◽  
Ectopic Expression ◽  
Nilaparvata Lugens ◽  
Effector Proteins ◽  
Salivary Proteins ◽  
Secretome Analysis

The brown planthopper (BPH), Nilaparvata lugens (Stål), is a phloem sap-feeding insect. During feeding on rice plants, BPH secretes salivary proteins with potential effector functions, which may play a critical role in the plant–insect interactions. However, a limited number of BPH effector proteins have been identified to date. Here, we sequenced the salivary gland transcriptomes of five BPH populations and subsequently established a N. lugens secretome consisting of 1,140 protein-encoding genes. Secretome analysis revealed the presence of both conserved and rapidly evolving salivary proteins. A screen for potential effectors that elicit responses in the plant was performed via the transient expression analysis of 64 BPH salivary proteins in Nicotiana benthamiana leaves and rice protoplasts. The salivary proteins Nl12, Nl16, Nl28, and Nl43 induced cell death, whereas Nl40 induced chlorosis and Nl32 induced a dwarf phenotype in N. benthamiana, indicating effector properties of these proteins. Ectopic expression of the six salivary proteins in N. benthamiana upregulated expression of defense-related genes and callose deposition. Tissue expression analysis showed a higher expression level of the six candidate effectors in salivary glands than in other tissues. Subcellular localization and analysis of the domain required for cell death showed a diverse structure of the six effectors. Nl28, Nl40, and Nl43 are N. lugens specific; in contrast, Nl12, Nl16, and Nl32 are conserved among insects. The Nl40 family has numerous isoforms produced by alternative splicing, exemplifying rapid evolution and expansion of effector proteins in the BPH. Our results suggest a potential large effector repertoire in BPH and a higher level of effector conservation exist in BPH compared with that in plant pathogens.

scholarly journals The mirid bug Apolygus lucorum deploys a glutathione peroxidase as a candidate effector to enhance plant susceptibility

2020 ◽  
Vol 71 (9) ◽  
pp. 2701-2712
Author(s):  
Yumei Dong ◽  
Maofeng Jing ◽  
Danyu Shen ◽  
Chenyang Wang ◽  
Meiqian Zhang ◽  
...  
Keyword(s):  
Cell Death ◽  
Salivary Gland ◽  
Glutathione Peroxidase ◽  
Large Scale ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Mechanism Analysis ◽  
Apolygus Lucorum ◽  
Mirid Bug ◽  
Plant Susceptibility

Abstract The mirid bug Apolygus lucorum has become a major agricultural pest since the large-scale cultivation of Bt-cotton. It was assumed that A. lucorum, similarly to other phloem sap insects, could secrete saliva that contains effector proteins into plant interfaces to perturb host cellular processes during feeding. However, the secreted effectors of A. lucorum are still uncharacterized and unstudied. In this study, 1878 putative secreted proteins were identified from the transcriptome of A. lucorum, which either had homology with published aphid effectors or shared common features with plant pathogens and insect effectors. One hundred and seventy-two candidate effectors were used for cell death-inducing/suppressing assays, and a putative salivary gland effector, Apolygus lucorum cell death inhibitor 6 (Al6), was characterized. The mRNAs of Al6 were enriched at feeding stages (nymph and adult) and, in particular, in salivary glands. Moreover, we revealed that the secreted Al6 encoded an active glutathione peroxidase that reduced reactive oxygen species (ROS) accumulation induced by INF1 or Flg22. Expression of the Al6 gene in planta altered insect feeding behavior and promoted plant pathogen infections. Inhibition of cell death and enhanced plant susceptibility to insect and pathogens are dependent on glutathione peroxidase activity of Al6. Thus, this study shows that a candidate salivary gland effector, Al6, functions as a glutathione peroxidase and suppresses ROS induced by pathogen-associated molecular pattern to inhibit pattern-triggered immunity (PTI)-induced cell death. The identification and molecular mechanism analysis of the Al6 candidate effector in A. lucorum will provide new insight into the molecular mechanisms of insect–plant interactions.

Morphological and molecular based identification of Antifungal bacillus licheniformis

2017 ◽  
Vol 17 (1) ◽  
pp. 31-35
Author(s):  
B Oyuntogtokh ◽  
M Byambasuren
Keyword(s):  
Bacillus Licheniformis ◽  
Fungal Pathogens ◽  
Crop Production ◽  
Plant Pathogens ◽  
Control Plant ◽  
Plant Diseases ◽  
Bacillus Species ◽  
Bacterial Strains ◽  
Fusarium Spp ◽  
Bacterial Cultures

At present, plant diseases caused by soil borne plant pathogens have major constraints on crop production. Which include genera Fusarium spp, Phytophtora spp, Sclerotinia and Altenaria. Due to this reason, chemical fungicides are routinely used to control plant disease, which is also true in Mongolian case. However, use of these chemicals has caused various problems including environmental pollution with consequence of toxicity to human health also resistance of some pathogens to these fungicides are present. Fortunately, an alternative method to reduce the effect of these plant pathogens is the use of antagonist microorganisms. Therefore, some species of the genus Bacillus are recognized as one of the most effective biological control agent.Our research was focused to isolate Bacillus licheniformis, with antifungal potential, from indigenous sources. In the current study, 28 bacterial cultures were isolated from soil and fermented mare’s milk also named as koumiss. Isolated bacterial cultures were identified according to simplified key for the tentative identification of typical strain of Bacillus species. As a result 8 strains were positive and further screened for antifungal activity against Fusarium spp and Alternaria solani. Out of these 8 strains 5 strains are selected based on their high effectiveness against fungal pathogens and for further confirmation Polymerase Chain reaction run for effective bacterial strains using specific primers B.Lich-f and B.Lich-r. 

scholarly journals Phytophthora infestans RXLR-WY effector AVR3a associates with a Dynamin-Related Protein involved in endocytosis of a plant pattern recognition receptor

2014 ◽  
Author(s):  
Angela Chaparro-Garcia ◽  
Simon Schwizer ◽  
Jan Sklenar ◽  
Kentaro Yoshida ◽  
Jorunn I. B. Bos ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Cell Death ◽  
Phytophthora Infestans ◽  
Plant Pathogens ◽  
Defense Responses ◽  
Effector Proteins ◽  
Related Protein ◽  
Receptor Mediated Endocytosis ◽  
Molecular Patterns ◽  
Basal Immunity

Perception of pathogen associated molecular patterns (PAMPs) by cell surface localized pattern recognition receptors (PPRs), activates plant basal defense responses in a process known as PAMP/PRR–triggered immunity (PTI). In turn, pathogens deploy effector proteins that interfere with different steps in PTI signaling. However, our knowledge of PTI suppression by filamentous plant pathogens, i.e. fungi and oomycetes, remains fragmentary. Previous work revealed that BAK1/SERK3, a regulatory receptor of several PRRs, contributes to basal immunity against the Irish potato famine pathogen Phytophthora infestans. Moreover BAK1/SERK3 is required for the cell death induced by P. infestans elicitin INF1, a protein with characteristics of PAMPs. The P. infestans host-translocated RXLR-WY effector AVR3a is known to supress INF1-mediated defense by binding the E3 ligase CMPG1. In contrast, AVR3aKI-Y147del, a deletion mutant of the C-terminal tyrosine of AVR3a, fails to bind CMPG1 and suppress INF1 cell death. Here we studied the extent to which AVR3a and its variants perturb additional BAK1/SERK3 dependent PTI responses using the plant PRR FLAGELLIN SENSING 2 (FLS2). We found that all tested variants of AVR3a, including AVR3aKI-Y147del, suppress early defense responses triggered by the bacterial flagellin-derived peptide flg22 and reduce internalization of activated FLS2 from the plasma membrane without disturbing its nonactivated localization. Consistent with this effect of AVR3a on FLS2 endocytosis, we discovered that AVR3a associates with the Dynamin-Related Protein DRP2, a plant GTPase implicated in receptor-mediated endocytosis. Interestingly, DRP2 is required for ligand-induced FLS2 internalization but does not affect internalization of the growth receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1). Furthermore, overexpression of DRP2 suppressed accumulation of reactive oxygen species triggered by PAMP treatment. We conclude that AVR3a associates with a key cellular trafficking and membrane-remodeling complex involved in immune receptor-mediated endocytosis and signaling. AVR3a is a multifunctional effector that can suppress BAK1/SERK3 mediated immunity through at least two different pathways.

scholarly journals Host targets of effectors of the lettuce downy mildew Bremia lactucae from cDNA-based yeast two-hybrid screening

2019 ◽  
Author(s):  
Alexandra J.E. Pelgrom ◽  
Claudia-Nicole Meisrimler ◽  
Joyce Elberse ◽  
Thijs Koorman ◽  
Mike Boxem ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Effector Proteins ◽  
Bremia Lactucae ◽  
Yeast Two Hybrid ◽  
Target Proteins ◽  
Successful Infection ◽  
Two Hybrid

AbstractPlant pathogenic bacteria, fungi and oomycetes secrete effector proteins to manipulate host cell processes to establish a successful infection. Over the last decade the genomes and transcriptomes of many agriculturally important plant pathogens have been sequenced and vast candidate effector repertoires were identified using bioinformatic analyses. Elucidating the contribution of individual effectors to pathogenicity is the next major hurdle. To advance our understanding of the molecular mechanisms underlying lettuce susceptibility to the downy mildew Bremia lactucae, we mapped a network of physical interactions between B. lactucae effectors and lettuce target proteins. Using a lettuce cDNA library-based yeast-two-hybrid system, 61 protein-protein interactions were identified, involving 21 B. lactucae effectors and 46 unique lettuce proteins. The top ten targets based on the number of independent colonies identified in the Y2H and two targets that belong to gene families involved in plant immunity, were further characterized. We determined the subcellular localization of the fluorescently tagged target proteins and their interacting effectors. Importantly, relocalization of effectors or targets to the nucleus was observed for four effector-target pairs upon their co-expression, supporting their interaction in planta.

scholarly journals RNA interference approaches for plant disease control

BioTechniques ◽  
2020 ◽  
Vol 69 (6) ◽  
pp. 469-477
Author(s):  
Yen-Wen Kuo ◽  
Bryce W Falk
Keyword(s):  
Rna Interference ◽  
Disease Control ◽  
Crop Production ◽  
Plant Disease ◽  
Plant Pathogens ◽  
Control Plant ◽  
Cost Effective ◽  
Plant Diseases ◽  
Natural Ecosystems ◽  
Plant Disease Control

Plant diseases caused by a variety of pathogens can have severe effects on crop plants and even plants in natural ecosystems. Despite many effective conventional approaches to control plant diseases, new, efficacious, environmentally sound and cost-effective approaches are needed, particularly with our increasing human population and the effects on crop production and plant health caused by climate change. RNA interference (RNAi) is a gene regulation and antiviral response mechanism in eukaryotes; transgenic and non transgenic plant-based RNAi approaches have shown great effectiveness and potential to target specific plant pathogens and help control plant diseases, especially when no alternatives are available. Here we discuss ways in which RNAi has been used against different plant pathogens, and some new potential applications for plant disease control.

scholarly journals Allelopathy and Agricultural Sustainability: Implication in weed management and crop protection—an overview

2019 ◽  
Vol 5 (2) ◽  
pp. 54-61
Author(s):  
Zahir Muhammad ◽  
Naila Inayat ◽  
Abdul Majeed ◽  
Hazrat Ali ◽  
Kaleem Ullah ◽  
...  
Keyword(s):  
Weed Management ◽  
Crop Production ◽  
Plant Pathogens ◽  
Crop Protection ◽  
Soil Health ◽  
Crop Plants ◽  
Plant Diseases ◽  
Agricultural Sustainability ◽  
Biotic And Abiotic Stresses ◽  
Diverse Plant

Abstract Crop plants have defined roles in agricultural production and feeding the world. They are affected by several environmental and biological stresses, which range from soil salinity, drought, and climate change to exposure to diverse plant pathogens. These stresses pose risk to agricultural sustainability. To avoid the increasing biotic and abiotic pressure on crop plants, agrochemicals are extensively used in agriculture for attaining desirable yield and production of crops. However, the use of agrochemicals is also challenging the integrity of ecosystems. Thus, to maintain the integrity of ecosystem, sustainable measures for elevated crop production are required. Allelopathy, a process of chemical interactions between plants and other organisms, could be used in the management of several biotic and abiotic stresses if the basic mechanisms of the phenomena and plants with allelopathic potentials are known. Allelopathy has a promising future for its application in agriculture for natural weed management, improving soil health and suppressing plant diseases. The aim of this review is to discuss the importance of allelopathy in agriculture and its role in sustainability with a specific focus on weed management and crop protection.

scholarly journals The CC domain structure from the wheat stem rust resistance protein Sr33 challenges paradigms for dimerization in plant NLR proteins

2016 ◽  
Vol 113 (45) ◽  
pp. 12856-12861 ◽  
Author(s):  
Lachlan W. Casey ◽  
Peter Lavrencic ◽  
Adam R. Bentham ◽  
Stella Cesari ◽  
Daniel J. Ericsson ◽  
...  
Keyword(s):  
Cell Death ◽  
Stem Rust ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Structural Basis ◽  
Wheat Stem Rust ◽  
Pathogen Effector ◽  
Resistance Protein ◽  
Cell Death Signaling ◽  
Self Association

Plants use intracellular immunity receptors, known as nucleotide-binding oligomerization domain-like receptors (NLRs), to recognize specific pathogen effector proteins and induce immune responses. These proteins provide resistance to many of the world’s most destructive plant pathogens, yet we have a limited understanding of the molecular mechanisms that lead to defense signaling. We examined the wheat NLR protein, Sr33, which is responsible for strain-specific resistance to the wheat stem rust pathogen, Puccinia graminis f. sp. tritici. We present the solution structure of a coiled-coil (CC) fragment from Sr33, which adopts a four-helix bundle conformation. Unexpectedly, this structure differs from the published dimeric crystal structure of the equivalent region from the orthologous barley powdery mildew resistance protein, MLA10, but is similar to the structure of the distantly related potato NLR protein, Rx. We demonstrate that these regions are, in fact, largely monomeric and adopt similar folds in solution in all three proteins, suggesting that the CC domains from plant NLRs adopt a conserved fold. However, larger C-terminal fragments of Sr33 and MLA10 can self-associate both in vitro and in planta, and this self-association correlates with their cell death signaling activity. The minimal region of the CC domain required for both cell death signaling and self-association extends to amino acid 142, thus including 22 residues absent from previous biochemical and structural protein studies. These data suggest that self-association of the minimal CC domain is necessary for signaling but is likely to involve a different structural basis than previously suggested by the MLA10 crystallographic dimer.

scholarly journals Effector proteins of extracellular fungal plant pathogens that trigger host resistance

2010 ◽  
Vol 37 (10) ◽  
pp. 901 ◽  
Author(s):  
Ann-Maree Catanzariti ◽  
David A. Jones
Keyword(s):  
Biological Activity ◽  
Host Resistance ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Host Tissue ◽  
Effector Proteins ◽  
Resistance Proteins ◽  
Recognitional Capacity ◽  
Fungal Plant Pathogens

An understanding of the molecular mechanisms that plant pathogens use to successfully colonise host tissue can be gained by studying the biological activity of pathogen proteins secreted during infection. Several secreted ‘effector’ proteins with possible roles in virulence have been isolated from extracellular fungal pathogens, including three that have been shown to negate host defences. In most cases, significant effector variation is observed between different pathogen isolates, driven by the recognitional capacity of disease resistance proteins arrayed against the pathogen by the host plant. This review summarises what is known about the expression, function and variation of effectors isolated from extracellular fungal pathogens.

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