Does Large-Scale Cropping of Herbicide-Resistant Cultivars Increase the Incidence of Polyphagous Soil-Borne Plant Pathogens?

2002 ◽  
Vol 31 (1) ◽  
pp. 51-54 ◽  
Author(s):  
A.J. Termorshuizen ◽  
L.A.P. Lotz
Keyword(s):  
Large Scale ◽  
Plant Pathogens ◽  
Herbicide Resistant ◽  
Resistant Cultivars

scholarly journals Integration of Stalk Destruction Methods for the Glyphosate Herbicide-Resistant Cotton

2022 ◽  
Vol 10 (2) ◽  
pp. 1
Author(s):  
Valdinei Sofiatti ◽  
Odilon RRF Silva ◽  
Edson R Andrade Junior ◽  
Alexandre CB Ferreira ◽  
Fabiano J Perina ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Cotton Stalk ◽  
Chemical Methods ◽  
Mechanical Destruction ◽  
Mato Grosso ◽  
Herbicide Resistant ◽  
Control Efficiency ◽  
Cotton Stalks ◽  
Chemical Destruction ◽  
Glyphosate Herbicide

The increase in geographical areas used for cultivation of transgenic glyphosate herbicide-resistant cotton has hindered the stalk destruction, compromised the phytosanitary break implementation and consequently increased the population of insect pests and cotton plant pathogens. This study evaluated the efficiency of the combining mechanical and chemical methods in the destruction of transgenic cotton stalk resistant to the glyphosate herbicide. Two experiments were carried out in 2015 and 2016 in Primavera do Leste,-Mato Grosso, Brazil and Luís Eduardo Magalhães, Bahia, Brazil, respectively. The study evaluated different mechanical destruction equipment in combination with the chemical methods. In each environment, a randomized block experiment with four replications was employed. The results of the experiments indicated that the mechanical destruction increased the control efficiency by at least 10% when compared to chemical destruction of the cotton stalk. Chemical destruction with herbicides combined with mechanical destruction methods does not increase the control efficiency of cotton stalks destruction. Furthermore, the application of hormonal herbicides following the mechanical shredding of cotton stalks does not increase the control efficiency of glyphosate-resistant cotton stalk.

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.

scholarly journals Oomycete metabolism is highly dynamic and reflects lifestyle adaptations

2020 ◽  
Author(s):  
Sander Y.A. Rodenburg ◽  
Dick de Ridder ◽  
Francine Govers ◽  
Michael F. Seidl
Keyword(s):  
Large Scale ◽  
Metabolic Networks ◽  
Plant Pathogens ◽  
Ecological Impact ◽  
Metabolic Enzymes ◽  
Network Analyses ◽  
Metabolic Adaptations ◽  
Parasitic Lifestyle ◽  
Defence Responses ◽  
The Relationship

SUMMARYPathogen-host symbiosis drives metabolic adaptations. Animal and plant pathogenic oomycetes are thought to adapt their metabolism to facilitate interactions with their hosts. Here, we performed a large-scale comparison of oomycete metabolism and uncovered considerable variation in oomycete metabolism that could be linked to differences in lifestyle. Pathway comparisons revealed that plant pathogenic oomycetes can be divided in two parts; a conserved part and an accessory part. The accessory part could be associated with the degradation of plant compounds produced during defence responses. Obligate biotrophic oomycetes have smaller metabolic networks, and this group displays converged evolution by repeated gene losses affecting the same metabolic pathways. A comparison of the metabolic networks of obligate biotrophic oomycetes with those of plant pathogenic oomycetes as a whole revealed that the losses of metabolic enzymes in biotrophs are not random and that the network of biotrophs contracts from the periphery inwards. Our analyses represent the first metabolism-focused comparison of oomycetes at this scale and will contribute to a better understanding of the evolution and relationship between metabolism and lifestyle adaptation.ORIGINALITY & SIGNFICANCE STATEMENTThe intimate interaction between pathogens and their hosts exerts strong selection pressure leading to rapid adaptation. How this shapes the metabolism of pathogens is largely unknown. Here, we used comparative genomics to systematically characterize the metabolisms of animal and plant pathogenic oomycetes, a group of eukaryotes comprising many important animal and plant pathogens with significant economic and ecological impact. Core- and pan-genome as well as metabolic network analyses of distantly related oomycetes and their non-pathogenic relatives revealed considerable lifestyle- and lineage-specific adaptations. Extreme lifestyle adaptation could be observed in the metabolism of obligate biotrophic oomycetes – a group of pathogens that require a living host for proliferation. The metabolic networks of obligate biotrophic oomycetes reflect profound patterns of reductive evolution, converging to a loss the same metabolic enzymes during acquisition of an obligate parasitic lifestyle. These findings contribute to a be better understanding of oomycete evolution and the relationship between metabolism and lifestyle adaptation.

scholarly journals Transcriptome Dynamics Underlying Chlamydospore Formation in Trichoderma virens GV29-8

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinhong Peng ◽  
Beilei Wu ◽  
Shuaihu Zhang ◽  
Mei Li ◽  
Xiliang Jiang
Keyword(s):  
Cell Cycle ◽  
Large Scale ◽  
Growth Stage ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Nitrogen Deficiency ◽  
Scale Production ◽  
Mycelium Growth ◽  
Growth Environment ◽  
Chlamydospore Formation

Trichoderma spp. are widely used biocontrol agents which are antagonistic to a variety of plant pathogens. Chlamydospores are a type of propagules produced by many fungi that have thick walls and are highly resistant to adverse environmental conditions. Chlamydospore preparations of Trichoderma spp. can withstand various storage conditions, have a longer shelf life than conidial preparations and have better application potential. However, large-scale production of chlamydospores has proven difficult. To understand the molecular mechanisms governing chlamydospore formation (CF) in Trichoderma fungi, we performed a comprehensive analysis of transcriptome dynamics during CF across 8 different developmental time points, which were divided into 4 stages according to PCA analysis: the mycelium growth stage (S1), early and middle stage of CF (S2), flourishing stage of CF (S3), and late stage of CF and mycelia initial autolysis (S4). 2864, 3206, and 3630 DEGs were screened from S2 vs S1, S3 vs S2, and S4 vs S3, respectively. We then identified the pathways and genes that play important roles in each stage of CF by GO, KEGG, STC and WGCNA analysis. The results showed that DEGs in the S2 vs S1 were mainly enriched in organonitrogen compound metabolism, those in S3 vs S2 were mainly involved in secondary metabolite, cell cycle, and N-glycan biosynthesis, and DEGs in S4 vs S3 were mainly involved in lipid, glycogen, and chitin metabolic processes. We speculated that mycelial assimilation and absorption of exogenous nitrogen in the early growth stage (S1), resulted in subsequent nitrogen deficiency (S2). At the same time, secondary metabolites and active oxygen free radicals released during mycelial growth produced an adverse growth environment. The resulting nitrogen-deficient and toxin enriched medium may stimulate cell differentiation by initiating cell cycle regulation to induce morphological transformation of mycelia into chlamydospores. High expression of genes relating to glycogen, lipid, mannan, and chitin synthetic metabolic pathways during the flourishing (S3) and late stages (S4) of CF may be conducive to energy storage and cell wall construction in chlamydospores. For further verifying the functions of the amino sugar and nucleotide sugar metabolism (tre00520) pathway in the CF of T. virens GV29-8 strain, the chitin synthase gene (TRIVIDRAFT_90152), one key gene of the pathway, was deleted and resulted in the dysplasia of mycelia and an incapability to form normal chlamydospores, which illustrated the pathway affecting the CF of T. virens GV29-8 strain. Our results provide a new perspective for understanding the genetics of biochemical pathways involved in CF of Trichoderma spp.

Influence of nitrogen fertilizers on yield and antifungal bioactivity of Tulbaghia violacea L.

2008 ◽  
Vol 27 (11) ◽  
pp. 851-857 ◽  
Author(s):  
E van den Heever ◽  
J Allemann ◽  
JC Pretorius
Keyword(s):  
Biological Activity ◽  
Antifungal Activity ◽  
Leaf Area ◽  
Large Scale ◽  
Plant Pathogens ◽  
Dry Mass ◽  
Application Rate ◽  
Nitrogen Fertilizers ◽  
Leaf Dry Mass

Tulbaghia is known to have antifungal properties that can be used in the treatment of both human and plant pathogens and is used in traditional medicine in South Africa. Increasing demands for plant material makes it necessary to cultivate this species on a large scale. Unfortunately, cultivation can lead to a reduction in the biological activity of plants making them unsuitable for use. In light of the lack of knowledge regarding the agronomic requirements of this plant, the aim of this study was to determine the effect of several rates and two forms of nitrogenous fertilizer on the yield and biological activity of Tulbaghia violacea. Plants were cultivated in sand while the basic fertilization used was the same as that of garlic (20 kg P ha−1, 75 kg K ha−1), a plant from the same family, containing similar active ingredients. Nitrogen was applied once at the beginning of the trial at rates of 30, 60, 120, and 180 kg ha−1 in the form of either nitrate or ammonium. Vegetative growth was quantified in terms of number of leaves and leaf area as well as root and leaf dry mass, while harvested material was tested for antifungal activity. The results indicated that compared with the untreated control, increasing N-rates in both the nitrate and ammonium forms increased leaf number and leaf area as well as both root and leaf dry mass. However, at a rate above 60 kg ha−1, and especially at 180 kg ha−1, the nitrate form stimulated growth more markedly than the ammonium form, whereas antifungal activity decreased sharply and almost linearly as the application rate was increased. Although growth was not stimulated to the same extent by the ammonium form, it increased the in-vitro antifungal activity at different levels during different times of the growing season. From an ornamental perspective, nitrate is the preferred nitrogenous form but, from a bioactivity perspective, ammonium is recommended.

scholarly journals A Chromosome-Scale Genome Assembly for the Fusarium oxysporum Strain Fo5176 To Establish a Model Arabidopsis-Fungal Pathosystem

2020 ◽  
Vol 10 (10) ◽  
pp. 3549-3555
Author(s):  
Like Fokkens ◽  
Li Guo ◽  
Susanne Dora ◽  
Bo Wang ◽  
Kai Ye ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Large Scale ◽  
Plant Pathogens ◽  
Single Copy ◽  
Model Systems ◽  
Fungal Genome ◽  
Suitable Model ◽  
Sequencing Data ◽  
High Coverage ◽  
Phylogenomic Analyses

Plant pathogens cause widespread yield losses in agriculture. Understanding the drivers of plant-pathogen interactions requires decoding the molecular dialog leading to either resistance or disease. However, progress in deciphering pathogenicity genes has been severely hampered by suitable model systems and incomplete fungal genome assemblies. Here, we report a significant improvement of the assembly and annotation of the genome of the Fusarium oxysporum (Fo) strain Fo5176. Fo comprises a large number of serious plant pathogens on dozens of plant species with largely unresolved pathogenicity factors. The strain Fo5176 infects Arabidopsis thaliana and, hence, constitutes a highly promising model system. We use high-coverage Pacific Biosciences Sequel long-read and Hi-C sequencing data to assemble the genome into 19 chromosomes and a total genome size of 67.98 Mb. The genome has a N50 of 4 Mb and a 99.1% complete BUSCO score. Phylogenomic analyses based on single-copy orthologs clearly place the Fo5176 strain in the Fo f sp. conglutinans clade as expected. We generated RNAseq data from culture medium and plant infections to train gene predictions and identified ∼18,000 genes including ten effector genes known from other Fo clades. We show that Fo5176 is able to infect cabbage and Brussel sprouts of the Brassica oleracea, expanding the usefulness of the Fo5176 model pathosystem. Finally, we performed large-scale comparative genomics analyses comparing the Fo5176 to 103 additional Fo genomes to define core and accessory genomic regions. In conjunction with the molecular tool sets available for A. thaliana, the Fo5176 genome and annotation provides a crucial step toward the establishment of a highly promising pathosystem.

scholarly journals Large-Scale Fungicide Spray Heterogeneity and the Regional Spread of Resistant Pathogen Strains

2006 ◽  
Vol 96 (5) ◽  
pp. 549-555 ◽  
Author(s):  
S. Parnell ◽  
F. van den Bosch ◽  
C. A. Gilligan
Keyword(s):  
Resistant Strain ◽  
Large Scale ◽  
Plant Pathogens ◽  
Regional Scale ◽  
Management Strategies ◽  
Resistance Management ◽  
Reproductive Capacity ◽  
Practical Significance ◽  
Free Fields ◽  
Disease Free

Most models for the spread of fungicide resistance in plant pathogens are focused on within-field dynamics, yet regional invasion depends upon the interactions between field populations. Here, we use a spatially implicit metapopulation model to describe the dynamics of regional spread, in which subpopulations correspond to single fields. We show that the criterion for the regional invasion of pathogens between fields differs from that for invasion within fields. That is, the ability of a fungicide-resistant strain of a pathogen to invade a field population does not necessarily imply an ability to spread through many fields at the regional scale. This depends upon an interaction between the fraction of fields that is sprayed and the reproductive capacity of the pathogen. This result is of practical significance and indicates that resistance management strategies which currently target within-field processes, such as the use of mixtures and alternations of fungicides, may be more effective if between-field processes also were targeted; for example, through the restricted deployment of fungicides over large areas. We also show that the fraction of disease-free fields is maximized when the proportion of fields that is sprayed is just below the threshold for invasion of the resistant strain.

scholarly journals Status of Chemical Alternatives to Methyl Bromide for Pre-Plant Fumigation of Soil

2002 ◽  
Vol 92 (12) ◽  
pp. 1337-1343 ◽  
Author(s):  
J. M. Duniway
Keyword(s):  
Methyl Bromide ◽  
Large Scale ◽  
Plant Pathogens ◽  
Production Systems ◽  
Growth Stimulation ◽  
Full Spectrum ◽  
Plant Materials ◽  
Metam Sodium ◽  
Significant Control ◽  
Plant Soil

None of the chemical alternatives currently registered and available has the full spectrum of activity and versatility of methyl bromide as a pre-plant soil fumigant. Chloropicrin and 1,3-dichloropropene (Telone) can provide significant control of many plant pathogens in soil and growth stimulation in annual crops. These compounds, however, provide limited control of weeds or other residual plant materials in soil of concern in nursery production systems, and some perennial replant diseases. Methyl isothiocyanate generators such as metam sodium have broad biocidal activity in soil, but are more difficult to apply effectively. In most soil applications, the available alternatives are likely to be used in combinations, either as mixtures (e.g., 1,3-dichloropropene and chloropicrin) or sequentially (e.g., chloropicrin followed by metam sodium). They may also be supplemented with other more specific pesticides and cultural controls. Among the alternatives currently under active development but not yet available, methyl iodide and propargyl bromide probably have activity that most closely parallels that of methyl bromide in soil. However, all of the chemical alternatives to methyl bromide will be subject to continuing review and more regulation. Furthermore, we do not know the actual prospects for registration of the new fumigants currently under development and there is a risk that registered fumigants will not be available for large-scale use in soil indefinitely.

scholarly journals Herbicide Resistance, Tillage, and Community Management in the Pacific Northwest

2021 ◽  
Vol 13 (4) ◽  
pp. 1937
Author(s):  
Katherine Dentzman ◽  
Ian Cristofer Burke
Keyword(s):  
Pacific Northwest ◽  
Herbicide Resistance ◽  
Large Scale ◽  
Conservation Tillage ◽  
Resistance Management ◽  
The United States ◽  
Community Management ◽  
Herbicide Resistant ◽  
The Pacific ◽  
Fail Safe

The use of glyphosate as a replacement for tillage has been credited with spurring the adoption of conservation tillage in the United States. With herbicide-resistant weeds becoming a significant agronomic problem, however, it is unclear whether conservation tillage gains are in danger of being reversed as farmers turn to tillage to manage weeds that herbicides can no longer kill. Using 2015 focus groups, a 2016 national survey, and an ongoing Community Herbicide Resistance Management Initiative in four communities of the Pacific Northwest we assess the following questions: (1) How do U.S. farmers view tillage as an option for controlling herbicide-resistant weeds, (2) Do attitudes towards and experience with herbicide-resistant increase farmers’ usage of tillage, and (3) Can community management provide an avenue for maintaining conservation tillage while also increasing effective management of herbicide-resistant weeds? We find that many farmers consider tillage to be an emergency fail-safe in managing weeds, that there is a complex relationship between herbicide resistance awareness, concern, and tillage use that can be partly explained by experience and dedication to conservation tillage, and finally that community management has the potential to provide the support and resources necessary to prevent a large-scale increase in tillage related to herbicide resistance management.

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