scholarly journals Fungal LysM effectors that comprise two LysM domains bind chitin through intermolecular dimerization

2020 ◽  
Author(s):  
Hui Tian ◽  
Gabriel L. Fiorin ◽  
Anja Kombrink ◽  
Jeroen R. Mesters ◽  
Bart P.H.J. Thomma
Keyword(s):  
Fungal Pathogens ◽  
Plant Immunity ◽  
Effector Proteins ◽  
Broad Host Range ◽  
Fungal Cell ◽  
Mould Fungus ◽  
Colletotrichum Higginsianum ◽  
Molecular Pattern ◽  
Wide Range ◽  
Binding Groove

SUMMARYChitin is a polymer of β-(1,4)-linked N-acetyl-D-glucosamine (GlcNAc) and a major structural component of fungal cell walls that acts as a microbe-associated molecular pattern (MAMP) that can be recognized by plant cell surface-localized pattern recognition receptors (PRRs) to activate a wide range of immune responses. In order to deregulate chitin-induced plant immunity and successfully establish their infection, many fungal pathogens secrete effector proteins with LysM domains. We previously determined that two of the three LysM domains of the LysM effector Ecp6 from the tomato leaf mould fungus Cladosporium fulvum cooperate to form a chitin-binding groove that binds chitin with ultra-high affinity, allowing to outcompete host PRRs for chitin binding. In this study, we describe functional and structural analyses aimed to investigate whether LysM effectors that contain two LysM domains bind chitin through intramolecular or intermolecular LysM dimerization. To this end, we focus on MoSlp1 from the rice blast fungus Magnaporthe oryzae, Vd2LysM from the broad host range vascular wilt fungus Verticillium dahliae, and ChElp1 and ChElp2 from the Brassicaceae anthracnose fungus Colletotrichum higginsianum. We show that these LysM effectors bind chitin through intermolecular LysM dimerization, allowing the formation of polymeric complexes that may precipitate in order to eliminate the presence of chitin oligomers at infection sites to suppress activation of chitin-induced plant immunity. In this manner, many fungal pathogens are able to subvert chitin-triggered immunity in their plant hosts.

scholarly journals Three LysM effectors of Zymoseptoria tritici collectively disarm chitin-triggered plant immunity

2020 ◽  
Author(s):  
Hui Tian ◽  
Craig I. MacKenzie ◽  
Luis Rodriguez-Moreno ◽  
Grardy C.M. van den Berg ◽  
Hongxin Chen ◽  
...  
Keyword(s):  
Plant Immunity ◽  
Effector Proteins ◽  
Septoria Tritici Blotch ◽  
Septoria Tritici ◽  
Zymoseptoria Tritici ◽  
Plant Host ◽  
Fungal Cell ◽  
Molecular Pattern ◽  
Fungal Hyphae ◽  
Ros Burst

SUMMARYChitin is a major structural component of fungal cell walls and acts as a microbe-associated molecular pattern (MAMP) that, upon recognition by a plant host, triggers the activation of immune responses. In order to avoid the activation of these responses, the Septoria tritici blotch (STB) pathogen of wheat, Zymoseptoria tritici, secretes LysM effector proteins. Previously, the LysM effectors Mg1LysM and Mg3LysM were shown to protect fungal hyphae against host chitinases. Furthermore, Mg3LysM, but not Mg1LysM, was shown to suppress chitin-induced reactive oxygen species (ROS) production. Whereas initially a third LysM effector gene was disregarded as a presumed pseudogene, we now provide functional data to show that also this gene encodes a LysM effector, named Mgx1LysM, that is functional during wheat colonization. While Mg3LysM confers a major contribution to Z. tritici virulence, Mgx1LysM and Mg1LysM contribute to Z. tritici virulence with smaller effects. All three LysM effectors display partial functional redundancy. We furthermore demonstrate that Mgx1LysM binds chitin, suppresses the chitin-induced ROS burst and is able to protect fungal hyphae against chitinase hydrolysis. Finally, we demonstrate that Mgx1LysM is able to undergo chitin-induced polymerisation. Collectively, our data show that Zymoseptoria tritici utilizes three LysM effectors to disarm chitin-triggered wheat immunity.

scholarly journals Synergistic Action of a Metalloprotease and a Serine Protease from Fusarium oxysporum f. sp. lycopersici Cleaves Chitin-Binding Tomato Chitinases, Reduces Their Antifungal Activity, and Enhances Fungal Virulence

2015 ◽  
Vol 28 (9) ◽  
pp. 996-1008 ◽  
Author(s):  
Mansoor Karimi Jashni ◽  
Ivo H. M. Dols ◽  
Yuichiro Iida ◽  
Sjef Boeren ◽  
Henriek G. Beenen ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Oxysporum ◽  
Serine Protease ◽  
Fungal Pathogens ◽  
Effector Proteins ◽  
Fungal Cell ◽  
Fungal Virulence ◽  
Chitin Binding Domain ◽  
Double Deletion ◽  
Major Structural Component

As part of their defense strategy against fungal pathogens, plants secrete chitinases that degrade chitin, the major structural component of fungal cell walls. Some fungi are not sensitive to plant chitinases because they secrete chitin-binding effector proteins that protect their cell wall against these enzymes. However, it is not known how fungal pathogens that lack chitin-binding effectors overcome this plant defense barrier. Here, we investigated the ability of fungal tomato pathogens to cleave chitin-binding domain (CBD)-containing chitinases and its effect on fungal virulence. Four tomato CBD chitinases were produced in Pichia pastoris and were incubated with secreted proteins isolated from seven fungal tomato pathogens. Of these, Fusarium oxysporum f. sp. lycopersici, Verticillium dahliae, and Botrytis cinerea were able to cleave the extracellular tomato chitinases SlChi1 and SlChi13. Cleavage by F. oxysporum removed the CBD from the N-terminus, shown by mass spectrometry, and significantly reduced the chitinase and antifungal activity of both chitinases. Both secreted metalloprotease FoMep1 and serine protease FoSep1 were responsible for this cleavage. Double deletion mutants of FoMep1 and FoSep1 of F. oxysporum lacked chitinase cleavage activity on SlChi1 and SlChi13 and showed reduced virulence on tomato. These results demonstrate the importance of plant chitinase cleavage in fungal virulence.

scholarly journals A secreted LysM effector protects fungal hyphae through chitin-dependent homodimer polymerization

2019 ◽  
Author(s):  
Andrea Sánchez-Vallet ◽  
Hui Tian ◽  
Luis Rodriguez-Moreno ◽  
Dirk-Jan Valkenburg ◽  
Raspudin Saleem-Batcha ◽  
...  
Keyword(s):  
Immune Responses ◽  
Cell Walls ◽  
Fungal Pathogens ◽  
Cladosporium Fulvum ◽  
Zymoseptoria Tritici ◽  
Fungal Cell ◽  
Lysm Domain ◽  
Fungal Hyphae ◽  
Binding Groove ◽  
Fungal Cell Walls

ABSTRACTPlants trigger immune responses upon recognition of fungal cell wall chitin, followed by the release of various antimicrobials, including chitinase enzymes that hydrolyze chitin. In turn, many fungal pathogens secrete LysM effectors that prevent chitin recognition by the host through scavenging of chitin oligomers. We previously showed that intrachain LysM dimerization of the Cladosporium fulvum effector Ecp6 confers an ultrahigh-affinity binding groove that competitively sequesters chitin oligomers from host immune receptors. Additionally, particular LysM effectors are found to protect fungal hyphae against chitinase hydrolysis during host colonization. However, the molecular basis for the protection of fungal cell walls against hydrolysis remained unclear. Here, we determined a crystal structure of the single LysM domain-containing effector Mg1LysM of the wheat pathogen Zymoseptoria tritici and reveal that Mg1LysM is involved in the formation of two kinds of dimers; a chitin-dependent dimer as well as a chitin-independent homodimer. In this manner, Mg1LysM gains the capacity to form a supramolecular structure by chitin-induced oligomerization of chitin-independent Mg1LysM homodimers, a property that confers protection to fungal cell walls against host chitinases.

scholarly journals The RXLR Effector PcAvh1 Is Required for Full Virulence of Phytophthora capsici

2019 ◽  
Vol 32 (8) ◽  
pp. 986-1000 ◽  
Author(s):  
Xiao-Ren Chen ◽  
Ye Zhang ◽  
Hai-Yang Li ◽  
Zi-Hui Zhang ◽  
Gui-Lin Sheng ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Plant Immunity ◽  
Phytophthora Capsici ◽  
Ectopic Expression ◽  
Plant Cells ◽  
Effector Proteins ◽  
Bell Pepper ◽  
Broad Host Range ◽  
Virus Induced Gene Silencing ◽  
Rxlr Effector

Plant pathogens employ diverse secreted effector proteins to manipulate host physiology and defense in order to foster diseases. The destructive Phytophthora pathogens encode hundreds of cytoplasmic effectors, which are believed to function inside the plant cells. Many of these cytoplasmic effectors contain the conserved N-terminal RXLR motif. Understanding the virulence function of RXLR effectors will provide important knowledge of Phytophthora pathogenesis. Here, we report the characterization of RXLR effector PcAvh1 from the broad–host range pathogen Phytophthora capsici. Only expressed during infection, PcAvh1 is quickly induced at the early infection stages. CRISPR/Cas9-knockout of PcAvh1 in P. capsici severely impairs virulence while overexpression enhances disease development in Nicotiana benthamiana and bell pepper, demonstrating that PcAvh1 is an essential virulence factor. Ectopic expression of PcAvh1 induces cell death in N. benthamiana, tomato, and bell pepper. Using yeast two-hybrid screening, we found that PcAvh1 interacts with the scaffolding subunit of the protein phosphatase 2A (PP2Aa) in plant cells. Virus-induced gene silencing of PP2Aa in N. benthamiana attenuates resistance to P. capsici and results in dwarfism, suggesting that PP2Aa regulates plant immunity and growth. Collectively, these results suggest that PcAvh1 contributes to P. capsici infection, probably through its interaction with host PP2Aa.

scholarly journals The role of the MAP kinase−kinase protein StMKK1 in potato immunity to different pathogens

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaokang Chen ◽  
Wenbin Wang ◽  
Pingping Cai ◽  
Ziwei Wang ◽  
Tingting Li ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Plant Immunity ◽  
Gray Mold ◽  
Mitogen Activated Protein Kinase ◽  
Necrotrophic Pathogen ◽  
Mapk Cascades ◽  
Molecular Pattern ◽  
Mitogen Activated Protein ◽  
Potato Resistance

AbstractMitogen-activated protein kinase (MAPK) cascades play important roles in plant immunity. Previously, we reported that the potato StMKK1 protein negatively regulates Nicotiana benthamiana resistance to Phytophthora infestans. However, the functions of StMKK1 in potato immunity are unknown. To investigate the roles of StMKK1 in potato resistance to different pathogens, such as the potato late-blight pathogen P. infestans, the bacterial wilt pathogen Ralstonia solanacearum, and the gray-mold fungal pathogen Botrytis cinerea, we generated StMKK1 transgenic lines and investigated the response of potato transformants to destructive oomycete, bacterial, and fungal pathogens. The results showed that overexpression and silencing of StMKK1 do not alter plant growth and development. Interestingly, we found that StMKK1 negatively regulated potato resistance to the hemibiotrophic/biotrophic pathogens P. infestans and R. solanacearum, while it positively regulated potato resistance to the necrotrophic pathogen B. cinerea. Further investigation showed that overexpression of StMKK1 suppressed potato pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and salicylic acid (SA)-related responses, while silencing of StMKK1 enhanced PTI and SA-related immune responses. Taken together, our results showed that StMKK1 plays dual roles in potato defense against different plant pathogens via negative regulation of PTI and SA-related signaling pathways.

scholarly journals Comparative genome analyses suggest a hemibiotrophic lifestyle and virulence differences for the beech bark disease fungal pathogens Neonectria faginata and Neonectria coccinea

2021 ◽  
Vol 11 (4) ◽  
Author(s):  
Catalina Salgado-Salazar ◽  
Demetra N Skaltsas ◽  
Tunesha Phipps ◽  
Lisa A Castlebury
Keyword(s):  
Fungal Pathogens ◽  
Beech Forest ◽  
Effector Proteins ◽  
Mitogen Activated Protein Kinase ◽  
Phylogenomic Analysis ◽  
Virulence Determinants ◽  
Beech Bark Disease ◽  
Molecular Physiology ◽  
Evolutionary Mechanisms ◽  
Wide Range

Abstract Neonectria faginata and Neonectria coccinea are the causal agents of the insect-fungus disease complex known as beech bark disease (BBD), known to cause mortality in beech forest stands in North America and Europe. These fungal species have been the focus of extensive ecological and disease management studies, yet less progress has been made toward generating genomic resources for both micro- and macro-evolutionary studies. Here, we report a 42.1 and 42.7 mb highly contiguous genome assemblies of N. faginata and N. coccinea, respectively, obtained using Illumina technology. These species share similar gene number counts (12,941 and 12,991) and percentages of predicted genes with assigned functional categories (64 and 65%). Approximately 32% of the predicted proteomes of both species are homologous to proteins involved in pathogenicity, yet N. coccinea shows a higher number of predicted mitogen-activated protein kinase genes, virulence determinants possibly contributing to differences in disease severity between N. faginata and N. coccinea. A wide range of genes encoding for carbohydrate-active enzymes capable of degradation of complex plant polysaccharides and a small number of predicted secretory effector proteins, secondary metabolite biosynthesis clusters and cytochrome oxidase P450 genes were also found. This arsenal of enzymes and effectors correlates with, and reflects, the hemibiotrophic lifestyle of these two fungal pathogens. Phylogenomic analysis and timetree estimations indicated that the N. faginata and N. coccinea species divergence may have occurred at ∼4.1 million years ago. Differences were also observed in the annotated mitochondrial genomes as they were found to be 81.7 kb (N. faginata) and 43.2 kb (N. coccinea) in size. The mitochondrial DNA expansion observed in N. faginata is attributed to the invasion of introns into diverse intra- and intergenic locations. These first draft genomes of N. faginata and N. coccinea serve as valuable tools to increase our understanding of basic genetics, evolutionary mechanisms and molecular physiology of these two nectriaceous plant pathogenic species.

scholarly journals The MicroRNA miR773 Is Involved in the Arabidopsis Immune Response to Fungal Pathogens

2018 ◽  
Vol 31 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Raquel Salvador-Guirao ◽  
Patricia Baldrich ◽  
Detlef Weigel ◽  
Ignacio Rubio-Somoza ◽  
Blanca San Segundo
Keyword(s):  
Fungal Pathogens ◽  
Adaptive Responses ◽  
Defense Gene Expression ◽  
Pathogen Infection ◽  
Defense Gene ◽  
Biotic Stresses ◽  
Molecular Pattern ◽  
Pathogen Challenge ◽  
Wide Range ◽  
Resistance To Infection

MicroRNAs (miRNAs) are 21- to 24-nucleotide short noncoding RNAs that trigger gene silencing in eukaryotes. In plants, miRNAs play a crucial role in a wide range of developmental processes and adaptive responses to abiotic and biotic stresses. In this work, we investigated the role of miR773 in modulating resistance to infection by fungal pathogens in Arabidopsis thaliana. Interference with miR773 activity by target mimics (in MIM773 plants) and concomitant upregulation of the miR773 target gene METHYLTRANSFERASE 2 (MET2) increased resistance to infection by necrotrophic (Plectosphaerrella cucumerina) and hemibiotrophic (Fusarium oxysporum, Colletototrichum higginianum) fungal pathogens. By contrast, both MIR773 overexpression and MET2 silencing enhanced susceptibility to pathogen infection. Upon pathogen challenge, MIM773 plants accumulated higher levels of callose and reactive oxygen species than wild-type plants. Stronger induction of defense-gene expression was also observed in MIM773 plants in response to fungal infection. Expression analysis revealed an important reduction in miR773 accumulation in rosette leaves of plants upon elicitor perception and pathogen infection. Taken together, our results show not only that miR773 mediates pathogen-associated molecular pattern-triggered immunity but also demonstrate that suppression of miR773 activity is an effective approach to improve disease resistance in Arabidopsis plants.

scholarly journals Molecular Mechanisms of Chitosan Interactions with Fungi and Plants

2019 ◽  
Vol 20 (2) ◽  
pp. 332 ◽  
Author(s):  
Federico Lopez-Moya ◽  
Marta Suarez-Fernandez ◽  
Luis Lopez-Llorca
Keyword(s):  
Cell Walls ◽  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Plant Immunity ◽  
Fungal Colonization ◽  
Fungal Cell ◽  
Physiological Basis ◽  
Mammalian Cell Lines ◽  
Root Interactions ◽  
Plant Chitinases

Chitosan is a versatile compound with multiple biotechnological applications. This polymer inhibits clinically important human fungal pathogens under the same carbon and nitrogen status as in blood. Chitosan permeabilises their high-fluidity plasma membrane and increases production of intracellular oxygen species (ROS). Conversely, chitosan is compatible with mammalian cell lines as well as with biocontrol fungi (BCF). BCF resistant to chitosan have low-fluidity membranes and high glucan/chitin ratios in their cell walls. Recent studies illustrate molecular and physiological basis of chitosan-root interactions. Chitosan induces auxin accumulation in Arabidopsis roots. This polymer causes overexpression of tryptophan-dependent auxin biosynthesis pathway. It also blocks auxin translocation in roots. Chitosan is a plant defense modulator. Endophytes and fungal pathogens evade plant immunity converting chitin into chitosan. LysM effectors shield chitin and protect fungal cell walls from plant chitinases. These enzymes together with fungal chitin deacetylases, chitosanases and effectors play determinant roles during fungal colonization of plants. This review describes chitosan mode of action (cell and gene targets) in fungi and plants. This knowledge will help to develop chitosan for agrobiotechnological and medical applications.

Control of Winged Waterprimrose (Jussiaea decurrens) and Northern Jointvetch (Aeschynomene virginica) with Fungal Pathogens

Weed Science ◽  
1979 ◽  
Vol 27 (5) ◽  
pp. 497-501 ◽  
Author(s):  
C. D. Boyette ◽  
G. E. Templeton ◽  
R. J. Smith
Keyword(s):  
Oryza Sativa ◽  
Glycine Max ◽  
Fungal Pathogens ◽  
Liquid Culture ◽  
Field Experiments ◽  
Colletotrichum Gloeosporioides ◽  
Pathogenic Fungus ◽  
Field Tests ◽  
Wide Range ◽  
Growing Region

An indigenous, host-specific, pathogenic fungus that parasitizes winged waterprimrose [Jussiaea decurrens(Walt.) DC.] is endemic in the rice growing region of Arkansas. The fungus was isolated and identified asColletotrichum gloeosporioides(Penz.) Sacc. f.sp. jussiaeae(CGJ). It is highly specific for parasitism of winged waterprimrose and not parasitic on creeping waterprimrose (J. repensL. var.glabrescensKtze.), rice (Oryza sativaL.), soybeans [Glycine max(L.) Merr.], cotton (Gossypium hirsutumL.), or 4 other crops and 13 other weeds. The fungus was physiologically distinct from C.gloeosporioides(Penz.) Sacc. f. sp.aeschynomene(CGA), an endemic anthracnose pathogen of northern jointvetch[Aeschynomene virginica(L.) B.S.P.], as indicated by cross inoculations of both weeds. Culture in the laboratory and inoculation of winged waterprimrose in greenhouse, growth chamber and field experiments indicated that the pathogen was stable, specific, and virulent in a wide range of environments. The pathogen yielded large quantities of spores in liquid culture. It is suitable for control of winged waterprimrose. Winged waterprimrose and northern jointvetch were controlled in greenhouse and field tests by application of spore mixtures of CGJ and CGA at concentrations of 1 to 2 million spores/ml of each fungus in 94 L/ha of water; the fungi did not damage rice or nontarget crops.

scholarly journals Revealing biophysical properties of KfrA-type proteins as a novel class of cytoskeletal, coiled-coil plasmid-encoded proteins

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
M. Adamczyk ◽  
E. Lewicka ◽  
R. Szatkowska ◽  
H. Nieznanska ◽  
J. Ludwiczak ◽  
...  
Keyword(s):  
Dna Binding ◽  
Host Range ◽  
Coiled Coil ◽  
Amino Acid Sequences ◽  
Broad Host Range ◽  
Biophysical Properties ◽  
Dna Binding Sites ◽  
In Silico Studies ◽  
Wide Range

Abstract Background DNA binding KfrA-type proteins of broad-host-range bacterial plasmids belonging to IncP-1 and IncU incompatibility groups are characterized by globular N-terminal head domains and long alpha-helical coiled-coil tails. They have been shown to act as transcriptional auto-regulators. Results This study was focused on two members of the growing family of KfrA-type proteins encoded by the broad-host-range plasmids, R751 of IncP-1β and RA3 of IncU groups. Comparative in vitro and in silico studies on KfrAR751 and KfrARA3 confirmed their similar biophysical properties despite low conservation of the amino acid sequences. They form a wide range of oligomeric forms in vitro and, in the presence of their cognate DNA binding sites, they polymerize into the higher order filaments visualized as “threads” by negative staining electron microscopy. The studies revealed also temperature-dependent changes in the coiled-coil segment of KfrA proteins that is involved in the stabilization of dimers required for DNA interactions. Conclusion KfrAR751 and KfrARA3 are structural homologues. We postulate that KfrA type proteins have moonlighting activity. They not only act as transcriptional auto-regulators but form cytoskeletal structures, which might facilitate plasmid DNA delivery and positioning in the cells before cell division, involving thermal energy.

Sign in / Sign up

Export Citation Format

Share Document