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 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.

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 Antagonistic effect of volatile and non-volatile compounds from Streptomyces strains on cultures of several phytopathogenic fungi

2020 ◽  
pp. 879
Author(s):  
Daniel Alonso Pérez Corral ◽  
José de Jesús Ornelas Paz ◽  
Guadalupe Isela Olivas Orozco ◽  
Carlos Horacio Acosta Muñiz ◽  
Miguel Ángel Salas Marina ◽  
...  
Keyword(s):  
Volatile Compounds ◽  
Fungal Pathogens ◽  
Culture Medium ◽  
Plant Pathogens ◽  
Aerial Mycelium ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Antagonistic Effect ◽  
Fresh Culture Medium

Fungi and oomycetes are important plant pathogens that constantly attacked plants, thus compromising the production of foods worldwide. Streptomyces strains might be useful to control fungal pathogens by different mechanism. The in vitro antagonistic activity of non-volatile and volatile metabolites from four Streptomyces strains was evaluated over cultures of phytopathogenic fungi and oomycetes. The non-volatile compounds from Streptomyces strains significantly reduced (44.2 to 92.1%) the growth of aerial mycelium of pathogens. The volatile compounds (VOCs) from Streptomyces strains reduced both aerial mycelium (22.5 to 96.7%) and mycelium growing inside of culture medium (0.0 - 9.4%). The pathogens maintained their capacity to grow normally in fresh culture medium without antagonists after confrontations with antagonist VOCs. The analysis of VOCs by gas chromatography coupled to mass spectrometry revealed different kinds of VOCs included alcohols, aldehydes, ketones, esters, terpenes, terpenoids, thioethers, among others. The most abundant VOCs were trans-1,10-dimethyl-trans-9-decalol (geosmin), 2-methylisoborneol, 2-methyl-2-bornene, 1,4-dimethyladamantane, and 4-penten-1-ol, trifluoroacetate. The antipathogenic activity of nine pure VOCs that had been identified in cultures of the Streptomyces strains alone was evaluated in vitro against phytopathogenic fungi and oomycetes. Trans-2-hexenal was the most effective of these VOCs, inhibiting completely the growth of tested phytopathogens. The volatile and non-volatile compounds from Streptomyces strains effectively reduced the in vitro growth of phytopathogens and they might be used as biological control. Further studies are required to demonstrate this activity on open field conditions.

scholarly journals Aplicaciones de la bacteria entomopatógena Bacillus thuringiensis en el control de fitopatógenos

2011 ◽  
Vol 12 (2) ◽  
pp. 129 ◽  
Author(s):  
Bertha Carreras S.
Keyword(s):  
Bacillus Thuringiensis ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Control Strategies ◽  
Wide Spectrum ◽  
Control Plant ◽  
Trichoderma Spp ◽  
Pseudomonas Spp ◽  
Biological Insecticide ◽  
Bacillus Spp

<p>El uso excesivo de plaguicidas químicos provoca resis tencia en los fitopatógenos, influencia negativa sobre el ambiente y la salud humana, por lo que se impone la implantación de estrategias de control de microorganismos benéficos, como Trichoderma spp., Bacillus spp., Pseudomonas spp. y otros agentes promisorios. Bacillus thuringiensis es el insecticida biológico más utilizado en el mundo para controlar diversos insectos y organismos plaga que afectan la agricultura, la actividad forestal y que transmiten patógenos a humanos y animales. En Cuba, los productos a base de B. thuringiensis se obtienen y se utilizan desde la década de los setenta del pasado siglo, y representan más del 40% de todos los controles biológicos. Actualmente, en el Instituto de Investigaciones de Sanidad Vegetal (INISAV) se cuenta con cepas de esta especie con efectos contra diferentes insectos y organismos plaga, lo cual permite disponer de una colección que cubre un espectro de numerosas plagas que afectan varios cultivos agrícolas; sin embargo, a pesar de la especificidad, virulencia, seguridad y potencia de estas cepas contra organismos patógenos, su potencial antifúngico es desconocido, aunque se sabe que esta bacteria produce una gran diversidad de metabolitos que resultan inhibitorios de hongos fitopatógenos. En esta revisión se citan las aplicaciones de B. thuringiensis en el control de organismos fitopatógenos y de la misma se deriva la importancia de explorar estas potencialidades en las cepas que conforman la colección de B. thuringiensis del INISAV como una alternativa más al control de fitopatógenos en Cuba.</p><p> </p><p><strong>Applications of entomopathogenic bacteria Bacillus thuringiensis to control phytopathogens.</strong></p><p>The overuse of chemical pesticides causes esistance in phytopathogens and negative influences on the environment and human health; therefore, the implementation of control strategies of beneficial microorganisms such as Trichoderma spp., Bacillus spp., Pseudomonas spp., and other promising agents is compelling. Bacillus thuringiensis is the most widely used biological insecticide in the world; it controls various insects and pests that affect agriculture and forestry and transmit pathogens to humans and animals. In Cuba, products based on B. thuringiensis were obtained and have been used since the 1970s, and they represent over 40% of all biological controls. Currently, the Plant Health Research Institute (INISAV) has various strains of this species that affect insects and pest organisms in different ways. This means they have a collection that covers a wide spectrum of the many diseases affecting various agricultural crops at their disposal. However, in spite of the recognized specificity, virulence, safety, and potency of these strains against pathogens, their antifungal potential is unknown, although it is known that this bacterium produces a variety of metabolites that inhibit fungal pathogens. In this review, we explore applications B. thuringiensis to control plant pathogenic organisms; from this, we derive the importance of exploring this potential in strains that make up the INISAV collection of B. thuringiensis as an alternative method to control plant pathogens in Cuba.</p>

scholarly journals Distribution and Identification of Endophytic Streptomyces Species from Schima wallichii as Potential Biocontrol Agents against Fungal Plant Pathogens

2016 ◽  
Vol 65 (3) ◽  
pp. 319-329 ◽  
Author(s):  
Ajit K. Passari ◽  
Vineet K. Mishra ◽  
Vijai K. Gupta ◽  
Ratul Saikia ◽  
Bhim P. Singh
Keyword(s):  
Medicinal Plants ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Fungal Pathogens ◽  
Biocontrol Agents ◽  
Rrna Gene ◽  
Streptomyces Species ◽  
Genus Streptomyces ◽  
Fungal Phytopathogens ◽  
Endophytic Streptomyces

The prospective of endophytic microorganisms allied with medicinal plants is disproportionally large compared to those in other biomes. The use of antagonistic microorganisms to control devastating fungal pathogens is an attractive and eco-friendly substitute for chemical pesticides. Many species of actinomycetes, especially the genus Streptomyces, are well known as biocontrol agents. We investigated the culturable community composition and biological control ability of endophytic Streptomyces sp. associated with an ethanobotanical plant Schima wallichi. A total of 22 actinobacterial strains were isolated from different organs of selected medicinal plants and screened for their biocontrol ability against seven fungal phytopathogens. Seven isolates showed significant inhibition activity against most of the selected pathogens. Their identification based on 16S rRNA gene sequence analysis, strongly indicated that all strains belonged to the genus Streptomyces. An endophytic strain BPSAC70 isolated from root tissues showed highest percentage of inhibition (98.3 %) against Fusarium culmorum with significant activity against other tested fungal pathogens. Phylogenetic analysis based on 16S rRNA gene sequences revealed that all seven strains shared 100 % similarity with the genus Streptomyces. In addition, the isolates were subjected to the amplification of antimicrobial genes encoding polyketide synthase type I (PKS-I) and nonribosomal peptide synthetase (NRPS) and found to be present in most of the potent strains. Our results identified some potential endophytic Streptomyces species having antagonistic activity against multiple fungal phytopathogens that could be used as an effective biocontrol agent against pathogenic fungi.

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 Photodynamic Inactivation reduces the diversity and changes the composition of bacterial and fungal communities associated with leaf surfaces

2021 ◽  
Author(s):  
Robert R. Junker ◽  
Lisa-Maria Ohler ◽  
Christoph Hamminger ◽  
Kristjan Plaetzer
Keyword(s):  
Plant Pathogens ◽  
Control Strategies ◽  
Microbial Community Composition ◽  
Amplicon Sequencing ◽  
Fungal Communities ◽  
Target Cells ◽  
Rrna Gene ◽  
Photodynamic Inactivation ◽  
Photodynamic Treatment ◽  
Leaf Surfaces

Plant surfaces are colonized by a myriad of microorganisms including mutualistic strains and pathogens. Particularly in agricultural systems applications are required that protect the plants against pathogens without negative side effects on the environment and humans. Photodynamic Inactivation (PDI) has been demonstrated to be a promising approach to efficiently fight plant pathogens. Based on its mechanism of action, the light-induced and photosensitizer-mediated overproduction of reactive oxygen species in target cells, PDI is likely to generally inactivates microorganisms on plants irrespective of their pathogenicity. In order to prove this hypothesis we used next-generation 16S rRNA gene amplicon sequencing to characterize the bacterial and fungal communities associated with leaf surfaces of Arabidopsis thaliana before and after the photodynamic treatment using the chlorine e6 derivative B17-0024 as photoactive compound and showed that this treatment reduced the microbial richness and altered the microbial community composition. These findings may help to develop effective pathogen-control strategies and may also stimulate research on plant-microbe interactions exploiting the potential of PDI.

scholarly journals Antifungal Activity of Endophytic Bacteria Associated with Sweet Sorghum (Sorghum bicolor)

2021 ◽  
Vol 53 (1) ◽  
pp. 16-30
Author(s):  
Siti Meliah ◽  
Tri Ratna Sulistiyani ◽  
Puspita Lisdiyanti ◽  
Atit Kanti ◽  
I Made Sudiana ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Sweet Sorghum ◽  
Endophytic Bacteria ◽  
Fungal Pathogens ◽  
Hydrolytic Enzymes ◽  
Antagonistic Activity ◽  
Lytic Enzyme ◽  
Rrna Gene ◽  
Antifungal Compound

The contribution of endophytic bacteria to the wellbeing of plants as biocontrol agents may be due to endophytic bacteria growing in the same niche as phytopathogens. This work was conducted to study the antagonistic activity of endophytic bacteria recovered from sweet sorghum against Sclerotium rolfsii, Fusarium solani, Fusarium oxysporum, Colletotrichum gloeosporioides in vitro and evaluate the mechanisms of these fungal inhibitions. We selected 78 endophytic bacteria from the stem and root of sweet sorghum plants. They were tested for antagonist activity by direct confrontation method. Antifungal compound production and lytic enzyme activity were examined to determine their mechanisms in inhibiting fungal pathogens. Antifungal compound production was checked by detecting the presence of NRPS and PKS genes. Lytic enzyme activity of the bacteria was evaluated by their ability to produce cellulase, chitinase, and protease. Selected bacteria were identified using molecular analysis based on the 16S rRNA gene. 14 out of the 78 tested isolates showed antagonistic activity and two were able to inhibit all four tested fungal strains. Four bacteria, designated as ACIL1, ACNM4, ACNM6, and ATNM4, produced natural products via NRPS pathway, but only one bacterial extract, designated as ACNM4, showed fungal inhibition. Ten isolates were able to produce hydrolytic enzymes. Endophytic bacteria identified as Burkholderia were revealed to have potential as a biocontrol agent.

scholarly journals Azole Use in Agriculture, Horticulture, and Wood Preservation – Is It Indispensable?

2021 ◽  
Vol 11 ◽  
Author(s):  
Lise Nistrup Jørgensen ◽  
Thies Marten Heick
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Control Strategies ◽  
Agricultural Practices ◽  
World Market ◽  
Plant Diseases ◽  
Wood Preservation ◽  
Modern Agriculture ◽  
Market Shares ◽  
High Yields

Plant pathogens cause significant damage to plant products, compromising both quantities and quality. Even though many elements of agricultural practices are an integral part of reducing disease attacks, modern agriculture is still highly reliant on fungicides to guarantee high yields and product quality. The azoles, 14-alpha demethylase inhibitors, have been the fungicide class used most widely to control fungal plant diseases for more than four decades. More than 25 different azoles have been developed for the control of plant diseases in crops and the group has a world market value share of 20-25%. Azoles have proven to provide long-lasting control of many target plant pathogens and are categorized to have moderate risk for developing fungicide resistance. Field performances against many fungal pathogens have correspondingly been stable or only moderately reduced over time. Hence azoles are still, to date, considered the backbone in many control strategies and widely used as solo fungicides or as mixing partners with other fungicide groups, broadening the control spectrum as well as minimizing the overall risk of resistance development. This review describes the historic perspective of azoles, their market shares and importance for production of major crops like cereals, rice, oilseed rape, sugar beet, banana, citrus, and soybeans. In addition, information regarding use in amenity grass, in the wood preservation industry and as plant growth regulators are described. At the end of the review azoles are discussed in a wider context including future threats following stricter requirements for registration and potential impact on human health.

scholarly journals Survey and Identification of Date Palm Pathogens and Indigenous Biocontrol Agents

Plant Disease ◽  
2020 ◽  
Vol 104 (9) ◽  
pp. 2498-2508
Author(s):  
Resna Nishad ◽  
Talaat A. Ahmed
Keyword(s):  
Endophytic Fungi ◽  
Fungal Pathogens ◽  
Date Palm ◽  
Defense Mechanism ◽  
Pathogenic Fungi ◽  
Antagonistic Activity ◽  
Immune Defense ◽  
Biocontrol Agents ◽  
Antifungal Metabolites ◽  
Different Seasons

Fungal diseases are considered a major threat to plant growth and productivity. However, some beneficial fungi growing in the same environment protect plants from various pathogens, either by secreting antifungal metabolites or by stimulating the host immune defense mechanism. Date palms are susceptible to several fungal pathogens. Nevertheless, information on the pathogenic fungal distribution in date palm fields across different seasons is limited, especially that from Qatar. Therefore, the current study’s aim was to evaluate the pathogenic and beneficial fungal diversity and distribution, including the endophytic fungi from the date palm tissues and root-associated soil fungi, during different seasons, for the identification of indigenous biocontrol agents. Our results showed that the highest number of fungal species was isolated in fall and spring, and pathogenic fungi were isolated mainly in spring. This is the first report that in Qatar, Neodeightonia phoenicum and Thielaviopsis punctulata cause date palm root rot disease, Fusarium brachygibbosum and Fusarium equiseti cause date palm wilting, and N. phoenicum causes diplodia disease in date palm offshoots. The combinations of the fungi that did not frequently occur together in date palm rhizosphere soil were investigated to identify indigenous biocontrol agents. Based on the results, we determined that Trichoderma harzianum and Trichoderma longibrachiatum are effective antagonistic fungi against T. punctulata, N. phoenicum, F. brachygibbosum, and Fusarium solani, qualifying them as potential biocontrol agents. Antagonistic activity of endophytic fungi against the pathogens was tested; except for Ulocladium chartarum, no endophytic fungi showed antagonistic activity against the tested pathogens. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

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