scholarly journals Means, motive, and opportunity for biological invasions: genetic introgression in a fungal pathogen

2021 ◽  
Author(s):  
Flávia Rogério ◽  
Cock van Oosterhout ◽  
Maisa Ciampi-Guillardi ◽  
Fernando Henrique Correr ◽  
Guilherme Kenichi Hosaka ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Population Genomics ◽  
Crop Yields ◽  
Control Strategies ◽  
Fungal Species ◽  
Genetic Introgression ◽  
Fungal Plant Pathogens ◽  
Genomic Studies

Invasions by fungal plant pathogens pose a significant threat to the health of agriculture ecosystems. Despite limited standing genetic variation, many invasive fungal species can adapt and spread rapidly, resulting in significant losses in crop yields. Here, we report on the population genomics of Colletotrichum truncatum, a polyphagous pathogen that can infect more than 460 plant species, and an invasive pathogen on soybean in Brazil. We study the whole-genome sequences of 18 isolates representing 10 fields from two major regions of soybean production. We show that Brazilian C. truncatum is subdivided into three phylogenetically distinct lineages that exchange genetic variation through hybridization. Introgression affects 2 to 30% of the nucleotides of genomes and varies widely between the lineages. We find that introgressed regions comprise secreted protein-encoding genes, suggesting possible co-evolutionary targets for selection in those regions. We highlight the inherent vulnerability of genetically uniform crops in the agro-ecological environment, particularly when faced with pathogens that can take full advantage of the opportunities offered by an increasingly globalized world. Finally, we discuss "The Means, Motive, and Opportunity" of fungal pathogens and how they can become invasive species of crops. We call for more population genomic studies because such analyses can help identify geographic areas and pathogens that pose a risk, thereby helping to inform control strategies to better protect crops in the future.

scholarly journals The emergence of cereal fungal diseases and the incidence of leaf spot diseases in Finland

2008 ◽  
Vol 20 (1) ◽  
pp. 62 ◽  
Author(s):  
M. JALLI ◽  
P. LAITINEN ◽  
S. LATVALA
Keyword(s):  
Spring Wheat ◽  
Leaf Spot ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Field Survey ◽  
Fungal Diseases ◽  
Cochliobolus Sativus ◽  
Pyrenophora Tritici Repentis ◽  
Fungal Plant Pathogens ◽  
First Time

Fungal plant pathogens causing cereal diseases in Finland have been studied by a literature survey, and a field survey of cereal leaf spot diseases conducted in 2009. Fifty-seven cereal fungal diseases have been identified in Finland. The first available references on different cereal fungal pathogens were published in 1868 and the most recent reports are on the emergence of Ramularia collo-cygni and Fusarium langsethiae in 2001. The incidence of cereal leaf spot diseases has increased during the last 40 years. Based on the field survey done in 2009 in Finland, Pyrenophora teres was present in 86%, Cochliobolus sativus in 90% and Rhynchosporium secalis in 52% of the investigated barley fields. Mycosphaerella graminicola was identified for the first time in Finnish spring wheat fields, being present in 6% of the studied fields. Stagonospora nodorum was present in 98% and Pyrenophora tritici-repentis in 94% of spring wheat fields. Oat fields had the fewest fungal diseases. Pyrenophora chaetomioides was present in 63% and Cochliobolus sativus in 25% of the oat fields studied.;

Localization and Visualization of Specific Gene Products in Fungal Plant Pathogens

2000 ◽  
Vol 6 (S2) ◽  
pp. 680-681 ◽  
Author(s):  
T. M. Bourett ◽  
K. J. Czymmek ◽  
T. M. Dezwaan ◽  
J. A. Sweigard ◽  
R. J. Howard
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Protein Localization ◽  
Infected Plant ◽  
Cell Interaction ◽  
Specific Gene ◽  
Gene Products ◽  
Tem Analysis ◽  
Fungal Plant Pathogens ◽  
Plant Pathogenesis

Specific gene products of both pathogens and hosts have been implicated as decisive elements during plant pathogenesis. While expression of some of these genes is constitutive, that of others is likely ephemeral and activated only during a particular stage of the interaction. Because the relative timing of expression may be critical, transcription and translation have often been addressed by extracting mRNA and proteins from infected plant tissue. This approach, however, cannot readily detect proteins of low abundance in bulk samples nor offer much useful information on cell-cell interaction. Only a cytological analysis that employs microscopy can resolve the temporal and spatial details of gene expression. Typically, such protein localization studies have required specific antibodies, but these large probe molecules do not diffuse into living or conventionally fixed cells of either fungal pathogens or plant hosts. For TEM analysis, these permeability-imposed limitations have been reduced by thin sectioning to render accessible antibody binding sites.

scholarly journals Nonhost Resistance in Arabidopsis-Colletotrichum Interactions Acts at the Cell Periphery and Requires Actin Filament Function

2006 ◽  
Vol 19 (3) ◽  
pp. 270-279 ◽  
Author(s):  
Chiyumi Shimada ◽  
Volker Lipka ◽  
Richard O'Connell ◽  
Tetsuro Okuno ◽  
Paul Schulze-Lefert ◽  
...  
Keyword(s):  
Actin Filament ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Fluorescent Protein ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Nonhost Resistance ◽  
Cell Periphery ◽  
Colletotrichum Species ◽  
Fungal Plant Pathogens

Pathogenesis of nonadapted fungal pathogens is often terminated coincident with their attempted penetration into epidermal cells of nonhost plants. The genus Colletotrichum represents an economically important group of fungal plant pathogens that are amenable to molecular genetic analysis. Here, we investigated interactions between Arabidopsis and Colletotrichum to gain insights in plant and pathogen processes activating nonhost resistance responses. Three tested nonadapted Colletotrichum species differentiated melanized appressoria on Arabidopsis leaves but failed to form intracellular hyphae. Plant cells responded to Colletotrichum invasion attempts by the formation of PMR4/GSL5-dependent papillary callose. Appressorium differentiation and melanization were insufficient to trigger this localized plant cell response, but analysis of nonpathogenic C. lagenarium mutants implicates penetration-peg formation as the inductive cue. We show that Arabidopsis PEN1 syntaxin controls timely accumulation of papillary callose but is functionally dispensable for effective preinvasion (penetration) resistance in nonhost interactions. Consistent with this observation, green fluorescent protein-tagged PEN1 did not accumulate at sites of attempted penetration by either adapted or nonadapted Colletotrichum species, in contrast to the pronounced focal accumulations of PEN1 associated with entry of powdery mildews. We observed extensive reorganization of actin microfilaments leading to polar orientation of large actin bundles towards appressorial contact sites in interactions with the nonadapted Colletotrichum species. Pharmacological inhibition of actin filament function indicates a functional contribution of the actin cytoskeleton for both preinvasion resistance and papillary callose formation. Interestingly, the incidence of papilla formation at entry sites was greatly reduced in interactions with C. higginsianum isolates, indicating that this adapted pathogen may suppress preinvasion resistance at the cell periphery.

scholarly journals Percolation-Based Risk Index for Pathogen Invasion: Application to Soilborne Disease in Propagation Systems

2013 ◽  
Vol 103 (10) ◽  
pp. 1012-1019 ◽  
Author(s):  
S. Poggi ◽  
F. M. Neri ◽  
V. Deytieux ◽  
A. Bates ◽  
W. Otten ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Control Strategies ◽  
Risk Index ◽  
Host Density ◽  
Transmission Probability ◽  
Pathogen Transmission ◽  
Soilborne Disease ◽  
Pathogen Invasion ◽  
Fungal Plant Pathogens ◽  
Set Up

Propagation systems for seedling growth play a major role in agriculture, and in notable cases (such as organic systems), are under constant threat from soil and seedborne fungal plant pathogens such as Rhizoctonia solani or Pythium spp. Yet, to date little is known that links the risk of disease invasion to the host density, which is an agronomic characteristic that can be readily controlled. We introduce here, for the first time in an agronomic system, a percolation framework to analyze the link. We set up an experiment to study the spread of the ubiquitous fungus R. solani in replicated propagation systems with different planting densities, and fit a percolation-based epidemiological model to the data using Bayesian inference methods. The estimated probability of pathogen transmission between infected and susceptible plants is used to calculate the risk of invasion. By comparing the transmission probability and the risk values obtained for different planting densities, we are able to give evidence of a nonlinear relationship between disease invasion and the inter-plant spacing, hence to demonstrate the existence of a spatial threshold for epidemic invasion. The implications and potential use of our methods for the evaluation of disease control strategies are discussed.

scholarly journals Population genomics reveals molecular determinants of specialization to tomato in the polyphagous fungal pathogen Botrytis cinerea in France

2021 ◽  
Author(s):  
Alex Mercier ◽  
Adeline Simon ◽  
Nicolas Lapalu ◽  
Tatiana Giraud ◽  
Marc Bardin ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Fungal Pathogen ◽  
Plant Pathogens ◽  
Population Genomics ◽  
Grey Mould ◽  
Host Specialization ◽  
Genomic Changes ◽  
Fungal Plant Pathogens ◽  
Synonymous Sites ◽  
Pathogen Populations

Many fungal plant pathogens encompass multiple populations specialized on different plant species. Understanding the factors underlying pathogen adaptation to their hosts is a major challenge of evolutionary microbiology, and it should help preventing the emergence of new specialized pathogens on novel hosts. Previous studies have shown that French populations of the grey mould pathogen Botrytis cinerea parasitizing tomato and grapevine are differentiated from each other, and have higher aggressiveness on their host-of-origin than on other hosts, indicating some degree of host specialization in this polyphagous pathogen. Here, we aimed at identifying the genomic features underlying the specialization of B. cinerea populations to tomato and grapevine. Based on whole genome sequences of 32 isolates, we confirmed the subdivision of B. cinerea pathogens into two genetic clusters on grapevine and another, single cluster on tomato. Levels of genetic variation in the different clusters were similar, suggesting that the tomato-specific cluster has not recently emerged following a bottleneck. Using genome scans for selective sweeps and divergent selection, tests of positive selection based on polymorphism and divergence at synonymous and non-synonymous sites and analyses of presence/absence variation, we identified several candidate genes that represent possible determinants of host specialization in the tomato-associated population. This work deepens our understanding of the genomic changes underlying the specialization of fungal pathogen populations.

scholarly journals Microbiota Associated with Sclerotia of Soilborne Fungal Pathogens – A Novel Source of Biocontrol Agents Producing Bioactive Volatiles

2019 ◽  
Vol 3 (2) ◽  
pp. 125-136 ◽  
Author(s):  
Pascal Mülner ◽  
Alessandro Bergna ◽  
Philipp Wagner ◽  
Dženana Sarajlić ◽  
Barbara Gstöttenmayr ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Control Strategies ◽  
Antagonistic Activity ◽  
Biocontrol Agents ◽  
High Yield ◽  
Rrna Gene ◽  
Strain Collection ◽  
Antifungal Volatiles ◽  
Differential Imaging

Soilborne plant pathogens are an increasing problem in modern agriculture, and their ability to survive long periods in soil as persistent sclerotia makes control and treatment particularly challenging. To develop new control strategies, we explored bacteria associated with sclerotia of Sclerotinia sclerotiorum and Rhizoctonia solani, two soilborne fungi causing high yield losses. We combined different methodological approaches to get insights into the indigenous microbiota of sclerotia, to compare it to bacterial communities of the surrounding environment, and to identify novel biocontrol agents and antifungal volatiles. Analysis of 16S rRNA gene fragment amplicons revealed significant compositional differences in the bacterial microbiomes of Rhizoctonia sclerotia, the unaffected tuber surface and surrounding soil. Moreover, distinctive bacterial lineages were associated with specific sample types. Flavobacteriaceae and Caulobacteraceae were primarily found in unaffected areas, while Phyllobacteriaceae and Bradyrhizobiaceae were associated with sclerotia of R. solani. In parallel, we studied a strain collection isolated from sclerotia of the pathogens for emission of bioactive volatile compounds. Isolates of Bacillus, Pseudomonas, and Buttiauxella exhibited high antagonistic activity toward both soilborne pathogens and were shown to produce novel, not yet described volatiles. Differential imaging showed that volatiles emitted by the antagonists altered the melanized sclerotia surface of S. sclerotiorum. Interestingly, combinations of bacterial antagonists increased inhibition of mycelial growth up to 60% when compared with single isolates. Our study showed that fungal survival structures are associated with a specific microbiome, which is also a reservoir for new biocontrol agents.

scholarly journals Cecropin A—Derived Peptides Are Potent Inhibitors of Fungal Plant Pathogens

1998 ◽  
Vol 11 (3) ◽  
pp. 218-227 ◽  
Author(s):  
Laura Cavallarin ◽  
David Andreu ◽  
Blanca San Segundo
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Crop Protection ◽  
Protective Effects ◽  
Tomato Plants ◽  
Hybrid Peptides ◽  
Cecropin A ◽  
Naturally Occurring ◽  
Fungal Plant Pathogens ◽  
Α Helix

Cecropins are naturally occurring peptides that play an important role in the immune response of insects. Cecropin A-derived and cecropin A-melittin hybrid peptides, all smaller than the natural compound cecropin A, were synthesized and tested for their ability to inhibit growth of several agronomically important fungal pathogens. We found that an 11-amino-acid sequence, corresponding to the N-terminal amphipathic α-helix domain of cecropin A, exhibited antifungal activity. Differences in susceptibility of the various pathogens were observed, Phytophthora infestans being particularly sensitive to the shortened cecropin A peptides (IC50 = 2 × 10−6 M). Biotoxicity of the shortest cecropin A-derived peptide was variously affected by the presence of proteins extracted from leaves of tobacco and tomato plants, either total extracts or intercellular fluids (ICFs). Overall, there was a greater tolerance to tomato protein extracts than to tobacco extracts. These findings suggest that tobacco should not be used as a model for testing the possible protective effects of transgenically expressed, cecropin-based genes. The feasibility of tailoring cecropin A genes to enhance crop protection in particular plant/fungus combinations is discussed.

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.

scholarly journals Natural gene drives offer potential pathogen control strategies in plants

2020 ◽  
Author(s):  
Donald M. Gardiner ◽  
Anca Rusu ◽  
Luke Barrett ◽  
Gavin C. Hunter ◽  
Kemal Kazan
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Control Strategies ◽  
Control Plant ◽  
Current Control ◽  
Plant Diseases ◽  
List Type ◽  
Gene Drive ◽  
Genetic Management ◽  
Pathogen Populations

SummaryGlobally, fungal pathogens cause enormous crop losses and current control practices are not always effective, economical or environmentally sustainable. Tools enabling genetic management of wild pathogen populations could potentially solve many problems associated with plant diseases.A natural gene drive from a heterologous species can be used in the globally important cereal pathogen, Fusarium graminearum, to remove pathogenic traits from contained populations of the fungus. The gene drive element became fixed in a freely crossing populations in only three generations.Repeat induce point mutation, a natural genome defence mechanism in fungi, may be useful to recall the gene drive following release, should a failsafe mechanism be required.We propose that gene drive technology is a potential tool to control plant pathogens.

scholarly journals Diversity of biocontrol agents, isolated from several sources, inhibitory to several fungal plant pathogens

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Yan Ramona ◽  
IDA BAGUS GEDE DARMAYASA ◽  
ANAK AGUNG NGURAH NARA KUSUMA ◽  
Martin Line
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Antagonistic Activity ◽  
Significant Inhibition ◽  
Biocontrol Agents ◽  
Dual Culture ◽  
Rdna Sequences ◽  
Fungal Plant Pathogens ◽  
Mature Compost

Abstract. Ramona Y, Darmayasa IBG, Kusuma AANN, Line MA. 2021. Diversity of biocontrol agents, isolated from several sources, inhibitory to several fungal plant pathogens. Biodiversitas 22: 298-303. This study investigated the inhibitory potential of diversity of antagonist bacteria residing in the rhizosphere zone and mature compost to counter fungal plant pathogens. Soils collected from rhizosphere of lettuce farms in Bali-Indonesia and Tasmania-Australia, mature compost, commercial biocontrol (Dipel®), and laboratory contaminants with significant inhibition against tested fungal pathogens were used as sources of antagonist bacteria. These antagonists were isolated by applying dilution and spread method on trypticase soya agar (TSA) or potato dextrose agar (PDA), and their ability to inhibit Sclerotinia minor, Sclerotinia sclerotiorum, Fusarium spp., and Rhizoctonia solani was assessed in dual culture assays. The results showed that 67 out of more than 100 isolates had antagonistic activity in vitro against at least one of tested fungal pathogens. In the preliminary identification, Bacillus spp. or Pseudomonas spp. were found to be pre-dominant isolates. Following screening studies in a non-replicated glasshouse experiment against S. minor and S. sclerotiorum, 8 of the most promising isolates were further identified using molecular methods based on their 16s rDNA sequences aligned with those deposited at the GeneBank. These 8 isolates were identified as Pseudomonas corrugata, Bacillus megaterium, Bacillus polymyxa, Bacillus mojavensis, Bacillus pumilus, Bacillus thuringiensis, Exiguobacterium acetylicum, and Chryseobacterium indologenes.

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